Find the First Palindrome

In this challenge, you will demonstrate your understanding of control flow in Rust. The task involves finding the first decimal palindrome in a given range.

What's a decimal palindrome?

A decimal palindrome is a number whose decimal (base 10, "normal") digits read the same backward as forward. This exercise will require you to find the numerically least non-negative palindrome in a given range. The easiest way to do this is to iterate through the range, check each number to see if it is a palindrome, and return the first palindrome found. You can use any control flow construct to solve this problem. (There are much more efficient ways to solve this problem, but the calculations get complex quickly.)

Palindromes are fascinating numbers, and finding them within a range will require clear control flow logic to ensure you identify the first one accurately.

Your task

You need to write a function, find_first_palindrome(start: i32, end: i32) -> Option<i32>, that takes two integer arguments start and end. The function should return the numerically least non-negative palindrome number within the range.

The range is inclusive: for example, if start == 1 and end == 1 the palindrome 1 is in range.
The range may have start > end, in which case it is still a valid range: for example, start == 3 and end == 1 contains the values 1, 2, 3.

If there are no palindromes in the range, the function should return None.

Requirements

The function should cover the numbers from start to end inclusive.
It should check each non-negative number to determine if it is a palindrome.
The function should return the numerically least palindrome found, or None if no palindromes exist in the range.
You must handle "reversed" ranges, when start is greater than end.

Example

let result = find_first_palindrome(10, 30);
assert_eq!(result, Some(11)); // 11 is the first palindrome in the range
 
let result = find_first_palindrome(100, 105);
assert_eq!(result, Some(101)); // 101 is the first palindrome in the range
 
let result = find_first_palindrome(123, 130);
assert_eq!(result, None); // No palindromes in this range
 
let result = find_first_palindrome(-130, -1);
assert_eq!(result, None); // No palindromes in this range
 
let result = find_first_palindrome(100, -105);
assert_eq!(result, Some(0)); // 0 is the first palindrome in the range

Did you know?

Did you know that palindromes are not just limited to numbers? They are found in words, phrases, and even DNA sequences! For example, the word "racecar" is a palindrome, as it reads the same backward and forward. Check out this "Weird Al" video for many many examples.

Palindromes are fascinating in various fields, including mathematics, literature, and biology, where they often have unique properties and significance.

Hints

To check if a number is a palindrome, you probably want to convert it to a String and compare it with its reverse.
You can get the chars in a String by using the chars() method on a String
You can iterate over values in reverse order by using the rev() method on an iterator. For example, you can get the chars in a String s in reverse order with s.chars().rev()
Use a loop, iterator, or any other control flow construct to check each number in the range until a palindrome is found or the range is exhausted.
Remember to handle the case where start is greater than end, probably by swapping the values if necessary.

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Solutions

GunGraveCpp

5 days ago

4.41ms

87.37kb

use std::mem::swap;
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let mut l = start;
    let mut r = end;
    
    if start > end{
        swap(&mut l, &mut r);
    }
    for num in l..=r{
        let st_num = num.to_string();
        for (idx, ch) in st_num.chars().rev().enumerate(){
            if ch != st_num.chars().nth(idx).unwrap(){
                break;
            }
            if idx + 1  == st_num.chars().count(){
                return Some(num);
            }
        }
    }
    None
}

aghia98

10 days ago

3.97ms

87.37kb

pub fn nbpos(num: i32) -> i8 {
    let mut a = num;
    let mut nbpos = 1;
    while a >= 10 {
        a = a/10;
        nbpos += 1;
    }
    nbpos
}
pub fn is_palindrome(num: i32) -> bool {
    
    let nbpos = nbpos(num);
    if nbpos == 1 {
        true
    } else {
        let middle_pos = nbpos/2;
        let mut vec: Vec<i32> = vec![];
        let mut a = num;
        let mut pal = true;
        for _ in 1..=middle_pos {
            vec.push(a%10);
            a /= 10;
        }
        if nbpos%2==1 {
            a/=10;
        }
        
        while let Some(digit) = vec.pop() {
            if digit != a%10 {
                pal = false;
                break;
            }
            a/=10;
        }
        pal
    }
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    if start<0 && end<0{
        return None;
    }
    if start<0 || end <0{
        return Some(0);
    }
    let (low, high) = if start <= end { (start, end) } else { (end, start) };
    (low..=high).find(|num| is_palindrome(*num))
}

manu3618

10 days ago

4.56ms

87.97kb

fn is_pal(n: i32) -> bool {
    let s = format!("{n}").chars().collect::<Vec<_>>();
    let mut r = s.clone();
    r.reverse();
    r == s
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let (a, b) = if end < start {
        (end, start)
    } else {
        (start, end)
    };
    for n in a..=b {
        if is_pal(n) {
            return Some(n);
        }
    }
    None
}

Heino Mortensen

hmortensen83

11 days ago

3.51ms

87.98kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let (start, end) = if start > end {
        (end, start)
    } else {
        (start, end)
    };
    for number in start..=end {
        let s = number.to_string();
        if s == s.chars().rev().collect::<String>() {
            return Some(number);
        }
    }
    None
}

Christophe Pronier

chrpron

18 days ago

3.35ms

87.37kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let deb: i32;
    let fin: i32;
    if start > end {
        deb = end;
        fin = start;
    } else {
        deb = start;
        fin = end;
    }
    for i in deb..=fin {
        let chain = format!("{i}");  
        if chain == chain.chars().rev().collect::<String>() {
            return Some(i);
        }
    } 
    None
}

Walter White

durgaprasad118

19 days ago

3.19ms

87.89kb

pub fn is_pal (num :i32)->bool{
    if num.to_string() == num.to_string().chars().rev().collect::<String>(){
        return true;
    }
    false
}
pub fn find_first_palindrome(mut start: i32, mut end: i32) -> Option<i32> {
      if end < start {
        (start, end) = (end, start);
    }
 // TODO: Implement the function here
    if start<0 && end<0{
        return None;
    }
    if start<0 || end <0{
        return Some(0);
    }
   
  
    for i in start..=end{
        if is_pal(i){
            return Some(i);
        }
    }
    None
}

Wouter

WouterMartens

24 days ago

3.35ms

87.99kb

fn is_palindrome(number: i32) -> bool {
    let chars: Vec<char> = number.to_string().chars().collect();
    let len = chars.len();
    let mid = len / 2;
    chars[..mid].iter().eq(chars[len - mid..].iter().rev())
}
pub fn find_first_palindrome(mut start: i32, mut end: i32) -> Option<i32> {
    if end < start {
        (start, end) = (end, start);
    }
    for i in start..=end {
        if is_palindrome(i) {
            return Some(i)
        }
    }
    None
}

whhc

a month ago

3.26ms

81.74kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let mut min_val = start.min(end);
    let max_val = start.max(end);
    min_val = min_val.max(0);
    (min_val..=max_val).find(|i| is_palindrome(*i))
}
pub fn is_palindrome(mut num: i32) -> bool {
    let original = num;
    let mut reversed = 0;
    while num > 0 {
        reversed = reversed * 10 + num % 10;
        num /= 10;
    }
    original == reversed
}

Andy Randrianirina

andyslash

a month ago

4.42ms

81.74kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let min_val = start.min(end);
    let max_val = start.max(end);
    let search_start = min_val.max(0);
    let search_end = max_val.max(0);
    
    if search_end < 0 {
        return None;
    }
    for num in search_start..=search_end {
        if is_palindrome(num) {
            return Some(num);
        }
    }
    None
}
pub fn is_palindrome(mut num: i32) -> bool {
    let original = num;
    let mut reversed = 0;
    while num > 0 {
        reversed = reversed * 10 + num % 10;
        num /= 10;
    }
    original == reversed
}

medzernik

a month ago

3.59ms

88.33kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let mut start_corrected = start;
    let mut end_corrected = end;
    if start >= end {
        start_corrected = end;
        end_corrected = start;
    }
    for i in start_corrected..=end_corrected {
        println!("NUMBER: {i}");
        let num_str = i.to_string().chars().collect::<Vec<char>>();
        for j in 0..num_str.len() {
            let first = j;
            let last = num_str.len() - j - 1;
            if num_str[first] != num_str[last] {
                println!("{} != {}", num_str[first], num_str[last]);
                break;
            }
            println!("{} {}", num_str[first], num_str[last]);
            return Some(i);
        }
    }
    None
}

Baron Curtin

baroncurtin2

a month ago

3.46ms

81.74kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let min_val = start.min(end);
    let max_val = start.max(end);
    let search_start = min_val.max(0);
    let search_end = max_val.max(0);
    // if range is entirely negative, no palindromes
    if search_end < 0 {
        return None;
    }
    for num in search_start..=search_end {
        if is_palindrome(num) {
            return Some(num);
        }
    }
    None
}
pub fn is_palindrome(mut num: i32) -> bool {
    let original = num;
    let mut reversed = 0;
    while num > 0 {
        reversed = reversed * 10 + num % 10;
        num /= 10;
    }
    original == reversed
}

Evrins Hu

evrins

a month ago

3.56ms

81.74kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let mut start = start;
    let mut end = end;
    if start > end {
        (start, end) = (end, start);
    }
    for num in start..=end {
        if is_palindrome(num) {
            return Some(num);
        }
    }
    None
}
fn is_palindrome(number: i32) -> bool {
    let mut num = number;
    let mut rev = 0;
    while num > 0 {
        rev = rev * 10 + num % 10;
        num /= 10;
    }
    rev == number
}

johndoe30bc

a month ago

3.25ms

81.74kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let is_palindrom = |n| {
        if n < 9 {
            return true;
        }
        let mut rest = n;
        let mut rev = 0;
        while rest > 0 {
            rev = rev * 10 + rest % 10;
            rest /= 10;
        }
        n == rev
    };
    let start = 0.max(start);
    let end = 0.max(end);
    let range = if start <= end {
        start..=end
    } else {
        end..=start
    };
    for n in range {
        if is_palindrom(n) {
            return Some(n);
        }
    }
    None
}

xxxxsk

a month ago

3.38ms

81.74kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let (min, max) = if start <= end {
        (start.max(0), end)
    } else {
        (end.max(0), start)
    };
    (min..=max).find(|&num| is_palindrome(num))
}
fn is_palindrome(mut value: i32) -> bool {
    if value < 0 {
        return false;
    }
    let original = value;
    let mut reversed = 0;
    while value > 0 {
        reversed = reversed * 10 + value % 10;
        value /= 10;
    }
    original == reversed
}

Evgenii Grigorenko

grevgeny

a month ago

3.29ms

81.74kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let (min, max) = if start <= end {
        (start.max(0), end)
    } else {
        (end.max(0), start)
    };
    (min..=max).find(|&num| is_palindrome(num))
}
fn is_palindrome(mut value: i32) -> bool {
    if value < 0 {
        return false;
    }
    let original = value;
    let mut reversed = 0;
    while value > 0 {
        reversed = reversed * 10 + value % 10;
        value /= 10;
    }
    original == reversed
}

brucecox01

a month ago

3.26ms

87.37kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let mut start = start;
    let mut end = end;
    if end < start {
        let t = end;
        end = start;
        start = t;
    }
    if start < 0 {
        start = 0;
    }
    while start <= end {
        let num = start.to_string();
        if num.chars().zip(num.chars().rev()).all(|(x,y)| x == y) {
            return Some(start);
        }
        start += 1;
    }
    None
}

Elliott Draper

ejdraper

a month ago

3.49ms

88.12kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    println!("start: {}, end: {}", start, end);
    let mut s = start;
    let mut e = end;
    if start > end {
        s = end;
        e = start;
    }
    if start == end && start == 1 {
        return Some(1);
    }
    for num in s..e {
        let fwd = num.to_string();
        let rev = num.to_string().chars().rev().collect::<String>();
        if fwd == rev {
            return Some(num);
        }
    }
    None
}

Neon-Panda

2 months ago

3.62ms

87.37kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let (start, end) = if start > end {
        (end, start)
    } else {
        (start, end)
    };
    for i in start..=end {
        let num_str = i.to_string();
        if num_str.chars().eq(num_str.chars().rev()) {
            return Some(i)
        }
    }
    None
}

Krzysztof Atłasik

katlasik

2 months ago

3.56ms

87.99kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    
    let (s,e) = if start > end {
        (end, start)
    } else {
        (start, end)
    };
    for number in s..=e {
        let number_str = number.to_string();
        let chars = number_str.chars();
        let mut chars_reversed = chars.clone().into_iter().collect::<Vec<char>>();
        chars_reversed.reverse();
        if chars.zip(chars_reversed).all(|(a,b)| a == b) {
            return Some(number)
        }
    }
    None
}

Alexander Y

unixander

2 months ago

3.15ms

87.37kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let mut end_ = end;
    let mut start_ = start;
    if start > end {
        let third = end;
        end_ = start;
        start_ = third;
    }
    
    for i in start_..=end_ {
        let chars = i.to_string();
        if chars.chars().eq(chars.chars().rev()) {
            return Some(i);
        }
    }
    None
}

Philippe Massicotte

PMassicotte

2 months ago

3.25ms

81.74kb

fn is_palindrome(mut n: i32) -> bool {
    if n < 0 {
        return false;
    }
    let original = n;
    let mut reversed = 0;
    while n > 0 {
        let digit = n % 10;
        reversed = reversed * 10 + digit;
        n /= 10;
    }
    original == reversed
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let a = start.min(end);
    let b = start.max(end);
    (a..=b).find(|&n| is_palindrome(n))
}

ggnne

2 months ago

4.10ms

87.37kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let a = if start > end {end} else {start};
    let b = if start > end {start} else {end};
    (a..=b).into_iter().filter(|n| {
        let a = n.to_string();
        a == a.chars().rev().collect::<String>()
    }).next()
}

Luigi Terrone

LuigiTer

2 months ago

3.34ms

87.98kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let (start, end) = if start <= end {
        (start, end)
    } else {
        (end, start)
    };
    let mut i: i32 = start;
    while i <= end {
        let x: String = i.to_string();
        let y: String = x.chars().rev().collect();
        if x == y {
            return Some(i);
        }
        i += 1;
    }
    None
}

Enes

enesscevik

2 months ago

3.77ms

87.98kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here    
    let (start, end) = if start < end {
        (start, end)
    } else {
        (end, start)
    };
    for i in start..=end {
        let st1 = i.to_string();
        let st2 : String = st1.chars().rev().collect();
        if st1 == st2 {
            return Some(i);
        }
    }
    None
}

ikatlinsky

2 months ago

3.81ms

87.98kb

fn is_a_palindrome(i: i32) -> bool {
    let s = format!("{i}");
    let reversed_s = s.chars().rev().collect::<String>();
    s == reversed_s
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    if start > end {
        return find_first_palindrome(end, start);
    }
    for i in start..=end {
        if is_a_palindrome(i) {
            return Some(i);
        }
    }
    None
}

Enriko

rix71

2 months ago

3.95ms

87.37kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    if start < 0 && end < 0{
       return None
    }
    let range_min = start.min(end);
    let range_start = if range_min >= 0 { range_min } else { 0 };
    let range_end = end.max(start);
    for num in range_start..=range_end {
        let num_str = num.to_string();
        let num_chars = num_str.chars();
        if num_chars.clone().zip(num_chars.rev()).map(|(a, b)| a == b).all(|b| b) {
            return Some(num);
        }
    }
    None
}

LeonardoPinheiro23

2 months ago

3.71ms

87.37kb

fn is_palindrome(number: i32) -> bool {
    let number = number.to_string();
    let last_index = number.len() - 1;
    let mid_index = number.len() / 2;
    let number = number.as_bytes();
    for index in 0..mid_index {
        if number[index] != number[last_index - index] {
            return false;
        }
    }
    true 
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let (start, end) = (start.min(end), start.max(end));
    for number in start..=end {
        if is_palindrome(number) {
            return Some(number);
        }
    } 
    None
}

annececiledunand

2 months ago

4.87ms

87.98kb

fn is_a_palindrome(i: i32) -> bool {
    let s: String = i.to_string();
    let reversed_s: String = s.chars().rev().collect();
    s == reversed_s
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    if start > end {
        // allow to reverse range mis-given args
        return find_first_palindrome(end, start);
    }
    for i in start..=end {
        if is_a_palindrome(i) {
            return Some(i);
        }
    }
    None
}

annececiledunand

2 months ago

3.15ms

87.98kb

fn is_a_palindrome(i: i32) -> bool {
    let s: String = format!("{i}");
    let reversed_s: String = s.chars().rev().collect();
    s == reversed_s
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    if start > end {
        // allow to reverse range mis-given args
        return find_first_palindrome(end, start);
    }
    for i in start..=end {
        if is_a_palindrome(i) {
            return Some(i);
        }
    }
    None
}

annececiledunand

2 months ago

3.32ms

87.98kb

fn is_a_palindrome(s: String) -> bool {
    let reversed_s: String = s.chars().rev().collect();
    s == reversed_s
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    if start > end {
        // allow to reverse range mis-given args
        return find_first_palindrome(end, start);
    }
    for i in start..=end {
        let i_as_str: String = format!("{i}");
        if is_a_palindrome(i_as_str) {
            return Some(i);
        }
    }
    None
}

Tommytto

3 months ago

3.49ms

87.99kb

fn is_palindrom(num: i32) -> bool {
    let s: Vec<char> = num.to_string().chars().collect();
    let mut left = 0;
    let mut right = s.len() - 1;
    while left < right {
        if s[left] == s[right] {
            left += 1;
            right -= 1;
        } else {
            return false;
        }
    } 
    true
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let (start, end) = if start > end { (end, start) }
    else { (start, end) };
    for num in start..=end {
        if is_palindrom(num) {
            return Some(num);
        }
    }
    None
}

Viktor Merkurev

fennr

3 months ago

4.65ms

87.40kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let (mut start, mut end) = (start, end);
    if start > end {
        (start, end) = (end, start);
    }
    (start..=end).find(|x| is_palindrome(*x))
}
fn is_palindrome(n: i32) -> bool {
    let str_n = n.to_string();
    str_n.chars().collect::<Vec<_>>() == str_n.chars().rev().collect::<Vec<_>>()
}

Liyqq

4 months ago

3.85ms

87.37kb

use std::cmp::{max, min};
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let (start, end) = (max(min(start, end), 0), max(start, end));
    (start..=end).find(|&num| {
        let num_str: String = num.to_string();
        let (forward, backward) = (num_str.chars(), num_str.chars().rev());
        forward.zip(backward).all(|c| c.0 == c.1)
    })
}

Liyqq

4 months ago

4.24ms

87.41kb

use std::cmp::{max, min};
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let (start, end) = (max(min(start, end), 0), max(start, end));
    (start..=end).find(|&num|
        num.to_string().chars().zip(num.to_string().chars().rev())
            .all(|c| c.0 == c.1)
    )
}

wertion555

4 months ago

4.58ms

88.00kb

pub fn find_first_palindrome(mut start: i32, mut end: i32) -> Option<i32> {
    if start > end {
        let temp = start;
        let temp2 = end;
        start = temp2;
        end = temp;
    }
    let mut palindromes = Vec::new();
    for num in start..=end {
        let num_str = num.to_string();
        if num_str == num_str.chars().rev().collect::<String>() {
            palindromes.push(num);
        }
    }
    return palindromes.first().copied();
}

Hung Dinh

nhdinh

4 months ago

5.73ms

87.99kb

use std::mem;
fn is_palindrome(n: i32) -> bool {
    let s = n.to_string();
    let chars = s.chars().collect::<Vec<_>>();
    let l = chars.len();
    for i in 0..l / 2 {
        if chars[i] != chars[l - i - 1] {
            return false;
        }
    }
    return true
}
pub fn find_first_palindrome(mut start: i32, mut end: i32) -> Option<i32> {
    if start > end {
        mem::swap(&mut start, &mut end);
    }
    for n in start..=end {
        if is_palindrome(n) {
            return Some(n);
        }
    }
    None
}

roboquaternion

4 months ago

3.56ms

87.45kb

pub fn is_palindrome(num: i32) -> bool {
    let s = num.to_string();    
    s == s.chars().rev().collect::<String>()
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // Create a RangeInclusive local variable in ascending order.
    let my_iter= if start<=end {
        start..=end
    } else {
        end..=start
    };
    
    my_iter
        .filter(|x| *x >= 0)            // ignore negative elements.
        .find(|&n| is_palindrome(n))    // Locate palindrome, return Option<i32>.        
}

vijayabhaskar badireddi

ptcte

4 months ago

4.31ms

87.37kb

fn check(n: i32) -> bool {
    let s = n.to_string();
    let rs: String = s.chars().rev().collect();
    s == rs
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    if start > 0 && end < 0 {
        return Some(0);
    } else if start < 0 && end < 0{
        return None;
    } else if start < 0 && end > 0 {
        return Some(0);
    } else {
        let start1;
        let end1;
        if start > end {
            end1 = start;
            start1 = end;
        } else {
            start1 = start;
            end1 = end;
        }
        for i in start1..=end1 {
            if check(i) {
                return Some(i);
            }
        }
    }
    None
}

Jakub Wiśniewski

wisniewskij

4 months ago

4.68ms

81.74kb

pub fn is_dec_palindrome(v: i32) -> bool {
    let mut cpy = v;
    let mut ans = 0;
    while cpy > 0 {
        ans = ans * 10 + cpy % 10;
        cpy /= 10;       
    }
    v == ans
}
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let mut start = start;
    let mut end = end;
    
    if start > end {
        std::mem::swap(&mut start, &mut end);
    }
    for i in start..=end {
        if i >= 0 && is_dec_palindrome(i) {
            return Some(i);
        }
    }
    None
}

Jason

Jason-fy-wang

4 months ago

3.32ms

87.98kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    if start == end {
        let forward = start.to_string();
        let reverse = forward.chars().rev().collect::<String>();
        if forward == reverse {
            return Some(start);
        }
    }
    if start < end {
        for v in start..=end {
            let forward = v.to_string();
            let reverse = forward.chars().rev().collect::<String>();
            if forward == reverse {
                return Some(v);
            }
        }
    }else{
        for v in end..=start {
            let forward = v.to_string();
            let reverse = forward.chars().rev().collect::<String>();
            if forward == reverse {
                return Some(v);
            }
        }
    }
    None
}

Aurimas Kuniutis

auriku

5 months ago

3.20ms

88.00kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    fn range(start: i32, end: i32) -> std::ops::RangeInclusive<i32> {
        if start > end {
            return end..=start;
        } else {
            start..=end
        }
    }
    let mut start = start;
    if start < 0 {
        start = 0;
    }
    for n in range(start, end) {
        if n.to_string().chars().collect::<String>()
            == n.to_string().chars().rev().collect::<String>()
        {
            return Some(n);
        }
    }
    None
}

Marcel Schiffel

mschiffel

5 months ago

4.49ms

87.45kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let from = start.min(end);
    let to = start.max(end);
    (from..=to).find(|number| {
        let forward = number.to_string();
        let reverse = forward.chars().rev().collect::<String>();
        forward == reverse
    })
}

syberianbull

5 months ago

3.72ms

87.98kb

use core::cmp::{min, max};
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let i = min(start, end);
    let j = max(start, end);
    for k in i..=j {
        let number = k.to_string();
        let reverse_number: String = number.chars().rev().collect();
        if number == reverse_number {
            return Some(k)
        }
    }
    None
}

Robbie K

va1ha11a

5 months ago

10.74ms

87.38kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let (bottom, top) = if start > end {
        (end, start)
    } else {
        (start, end)
    };
    for i in bottom..top + 1 {
        if i.to_string() == i.to_string().chars().rev().collect::<String>() {
            return Some(i);
        }
    }
    None
}

VerweyFr

5 months ago

4.98ms

87.38kb

use std::cmp;
pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let _start = cmp::min(start, end);
    let _end = cmp::max(start, end);
    for v in _start..=_end {
        let s1 = v.to_string();
        let s2: String = v.to_string().chars().rev().collect();
        if s1 == s2 {
            return Some(v);
        }
    }
    None
}

Yixian Du

duyixian1234

5 months ago

3.87ms

87.98kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let min: i32;
    let max: i32;
    if start < end { 
        min = start;
        max = end;
    } else {
        min = end;
        max = start;
    }
    for number in min..=max {
        let s = number.to_string();
        let r: String = s.chars().rev().collect();
        if s == r { 
            return Some(number) 
        }
    }
    None
}

gsspdev

5 months ago

4.84ms

87.98kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let min: i32;
    let max: i32;
    if start < end { 
        min = start;
        max = end;
    } else {
        min = end;
        max = start;
    }
    for number in min..=max {
        let s = number.to_string();
        let r: String = s.chars().rev().collect();
        if s == r { 
            return Some(number) 
        }
    }
    None
}

lugtester

5 months ago

3.18ms

87.38kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let (mut begin, mut finish) = (start, end);
    if start > end {
        (begin, finish) = (end, start);
    }
    for i in begin..=finish {
        if i.to_string() == i.to_string().chars().rev().collect::<String>() {
            return Some(i);
        }
    }
    None
}

panda wiz

pandamrx

5 months ago

3.66ms

87.40kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    // TODO: Implement the function here
    let mut start_copy = start;
    let mut end_copy = end;
    if start > end {
        start_copy = end;
        end_copy = start;
    }
    for i in start_copy..=end_copy {
        let num = i.to_string();
        let chars: Vec<char> = num.to_lowercase().chars().collect();
        let chars_rev: Vec<char> = num.to_lowercase().chars().collect();
        let last_index = chars.len() - 1;
        for j in 0..chars.len() {
            if chars[j] != chars_rev[last_index - j] {
                break;
            }
            if j == chars.len() - 1 {
                return Some(i);
            }
        }
    }
    None
}

Anna Komarova

Vlasanya

5 months ago

4.44ms

87.98kb

pub fn find_first_palindrome(start: i32, end: i32) -> Option<i32> {
    let lower = start.min(end);
    let upper = start.max(end);
    
    for n in lower..=upper {
        if n < 0 {
            continue;
        }
        let s = n.to_string();
        let rev: String = s.chars().rev().collect();
        if s == rev {
            return Some(n);
        }
    }
    None
}