Mutable Slices

In this challenge, you'll explore how to work with mutable slices in Rust. A mutable slice, &mut [T], allows you to modify the elements of a collection directly and efficiently without creating a new collection.

Slices are a fundamental part of Rust, providing a view into contiguous sequences of elements such as arrays or vectors. When working with slices, you can iterate over and manipulate the elements dynamically.

Your Task

Write a function modify_elements(slice: &mut [i32]) that modifies the elements of a mutable slice of integers in the following way:

Double each even number in the slice.
Subtract 1 from each odd number in the slice.
Modify the elements directly without creating a new collection.

Example

let mut numbers = [1, 2, 3, 4, 5];
modify_elements(&mut numbers);
 
// Odd numbers reduced by 1
// Even numbers doubled
assert_eq!(numbers, [0, 4, 2, 8, 4]);
 
let mut numbers = [10, 15, 20];
modify_elements(&mut numbers);
 
// 10 -> 20, 15 -> 14, 20 -> 40
assert_eq!(numbers, [20, 14, 40]);

Hints

If you're stuck, here are some hints to help you:

Additional Hints

Use the .iter_mut() method to traverse the slice by mutable reference.
Remember that you can check if a number is even using num % 2 == 0.
Use dereferencing (*) to update the value pointed to by the mutable reference.
You can use a for loop with mutable references for concise modification.
The slice directly modifies the original collection it is derived from, so no need to return anything.

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Solutions

Adrian Stanciu

stanciuadrian

5 hours ago

5.25ms

90.57kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for elem in slice {
        println!("{}", elem);
        match *elem % 2 {
            0 => *elem *= 2,
            1 | -1 => *elem -= 1,
            _ => unreachable!(),
        }
    }
}

sn00py-lays

10 hours ago

4.26ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for x  in slice.iter_mut(){
        if *x % 2 == 0{
            *x = *x * 2
        } else {
            *x = *x - 1
        }
    }
}

olivaresrafael

a day ago

4.23ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for elem in slice.iter_mut(){
        if *elem % 2 == 0 {
            *elem = *elem * 2;
        } else {
            *elem = *elem - 1;
        }
    }
}

Rubén Moreno aguado

rmaguado

2 days ago

5.09ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for item in slice.iter_mut() {
        if *item % 2 == 0 {
            *item = *item * 2;
        } else {
            *item = *item - 1;
        }
    }
}

Rubén Moreno aguado

rmaguado

2 days ago

4.69ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for item in slice.iter_mut() {
        if *item % 2 == 0 {
            *item = *item * 2;
        } else {
            *item = *item - 1;
        }
    }
}

yqmt8708

2 days ago

4.74ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for x in slice.iter_mut() {
        if *x%2 == 0 {
            *x *= 2;
        }
        else {
            *x -= 1;
        }
    }
}

yqmt8708

2 days ago

6.55ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for x in slice.iter_mut() {
        if *x%2 == 0 {
            *x *= 2;
        }
        else {
            *x -= 1;
        }
    }
}

Valtteri Äyräs

walterairs

2 days ago

5.68ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for item in slice.iter_mut() {
        if *item % 2 == 0 {
            *item = *item * 2;
            continue
        } else {
            *item -= 1
        }
    }
}

ttenroK

2 days ago

4.66ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for number in slice {
        if *number % 2 == 0
        {
            *number *= 2;
        }
        else {
            *number -= 1;
        }
    }
}

something238892

3 days ago

5.20ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for i in slice {
        if *i % 2 == 0 {
            *i *= 2;
        } else {
            *i -= 1;
        }
    }
}

Bastien VINH

bastienvinh

3 days ago

5.04ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for val in slice.iter_mut() {
        if *val % 2 == 0 {
            *val *= 2; // Multiply odd numbers by
        } else {
            *val -= 1;
        }
    }
}

ychanghe

3 days ago

4.63ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for v in slice.iter_mut(){
        if *v%2 == 0{
            *v = 2**v
        }
        else {
            *v -= 1 
        }
    }
}

Omar Saber Talaat Abdelrahman

omar-s-ta

3 days ago

5.00ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    slice.iter_mut().for_each(|x| {
        if *x % 2 == 0 {
            *x *= 2;
        } else {
            *x -= 1;
        }
    });
}

Omar Saber Talaat Abdelrahman

omar-s-ta

3 days ago

4.51ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for e in slice.iter_mut() {
        if *e % 2 == 0 {
            *e *= 2;
        } else {
            *e -= 1;
        }
    }
}

SeokwonJung-Jay

3 days ago

5.96ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for s in slice.iter_mut() {
        if *s % 2 == 0 {
            *s = *s * 2;
        }
        else {
            *s = *s - 1;
        }
    }
}

TM

gausam

4 days ago

4.31ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for n in slice.iter_mut() {
        *n = if *n % 2 == 0 {
            *n * 2
        } else {
            *n - 1
        };
    }
}

Jule Lissajou

LissajouAn

4 days ago

5.04ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for i in slice.iter_mut() {
        if *i % 2 == 0 {
            *i = *i * 2;
        } else {
            *i = *i - 1
        }
    }
}

Bl4d3

DhruvJ2

4 days ago

7.30ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for num in slice.iter_mut() {
        if *num % 2 == 0 {
            *num *= 2;
        } else {
            *num -= 1;
        }
    }
}

Ari Karim

arikarim

4 days ago

4.84ms

89.23kb

    pub fn transform_even_odd(slice: &mut [i32]) {
        // Your code here: iterate over the mutable slice and modify its elements.
        slice.iter_mut().for_each(|el| {
            *el = match *el % 2 {
                0 => *el * 2,
                _ => *el - 1,
            };
        });
    }

/sam

samging

5 days ago

6.07ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for num in slice.iter_mut() {
        if *num % 2 == 0 {
            *num *= 2;
        } else {
            *num -= 1;
        }
    }
}

2Madre

5 days ago

22.96ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for i in slice.iter_mut() {
        if *i % 2 == 0 {
            *i = *i * 2;
        } else {
            *i = *i-1;
        }
    }
}

Nicky Zaguine

HunterNicky

5 days ago

6.73ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for _num in slice.iter_mut() {
        if *_num % 2 == 0 {
            *_num = *_num * 2;
        }
        else {
            *_num = *_num - 1;
        }
    }
}

Kishan

wdcs-kishansudani

5 days ago

4.92ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for number in slice {
        if *number % 2 == 0 {
            *number *= 2;
        } else {
            *number -= 1;
        }
    }
}

JacobWarners

5 days ago

4.26ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for i in slice.iter_mut() {
        if *i % 2 == 0 {
            *i *= 2
        
    }else {
        *i -= 1
      }
}
}

Dr. Frederik Lauber

FrederikLauber

7 days ago

6.62ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for element in slice.iter_mut() {
        if *element % 2 == 0 {
            *element = *element * 2;
        } else {
            *element = *element - 1;
        }
    }
}

Swissy

swissyp

7 days ago

5.05ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for i in slice.iter_mut() {
        if *i % 2 == 0 {
            *i *= 2
        } else {
            *i -= 1
        }
    }
}

Erik Zhao

zhaoerik

8 days ago

4.14ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for n in slice.iter_mut() {
        if *n % 2 == 0 {
            *n *= 2
        } else {
            *n -= 1
        }
    }
}

Rácz Zoltán

zolitheman648

8 days ago

4.56ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for slice_num in slice.iter_mut() {
        if *slice_num % 2 != 0 {
            *slice_num -= 1
        } else {
            *slice_num *= 2
        }
    }
}

traderdude123

8 days ago

5.72ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for i in slice {
        if *i % 2 == 0 {
            *i = *i * 2;
        }
        else {
            *i = *i - 1;
        }
    }
}

ibrahimomar9316

8 days ago

5.69ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for n in slice.iter_mut(){
        if *n % 2 == 0 {
            *n *= 2
        }
        else {
            *n -= 1
        }
    }
}
//alternative solution
/*
for i in 0..slice.len() {
        if slice[i] % 2 == 0 {
            slice[i] *= 2;
        } else {
            slice[i] -= 1;
        }
    }
*/

daz

mintydevdaz

8 days ago

5.44ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for n in slice.iter_mut() {
        if *n % 2 == 0 {
            *n *= 2;
        } else {
            *n -= 1;
        }
    }
}

matthew-snyder

9 days ago

5.27ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for x in slice.iter_mut() {
        if *x % 2 == 0 {
            *x *= 2
        }
        else{
            *x -= 1
        }
    }
}

Luigi

luigiistcrazy

9 days ago

5.46ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for n in slice.iter_mut(){
        if *n % 2 == 0 {
            *n *= 2
        } else {
            *n -= 1
        }
    }
}

hidethere

9 days ago

4.27ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    modify_elements(slice);
}
pub fn modify_elements (slice: &mut [i32]) {
    for i in slice.iter_mut(){
        if *i % 2 == 0 {
            *i = *i * 2;
        } else {
            *i = *i - 1;
        }
    }
}

tommy759

9 days ago

4.18ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for i in slice.iter_mut() {
        match *i%2 {
            0 => *i *= 2,
            _ => *i -= 1,
        }
    }
}

Fetisov Roman

Unstate

9 days ago

4.54ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for element in slice.iter_mut() {
        if *element % 2 == 0 {
            *element *= 2;
        } else {
            *element -= 1;
        }
    }
}

yrd241

9 days ago

4.29ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for i in slice {
        if *i % 2 != 0 {
            *i -= 1;
        }else {
            *i *= 2;
        }
    }
}

Zach Boyce

ZachBoyce1

9 days ago

4.24ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for i in slice {
        if *i % 2 == 0 {
            *i = *i * 2;
        } else {
            *i = *i - 1;
        }
    }
}

Mark Cafazzo

capacitive

10 days ago

4.97ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for num  in slice.iter_mut() {
        if *num % 2 == 0 {
            *num *= 2;
        } else {
            *num -= 1;
        }
    }
}
pub fn main () {
    return 
}

Yummy-Yums

10 days ago

5.72ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for num in slice.iter_mut() {
        if *num % 2 == 0 {
            *num *= 2;
        } else {
            *num -= 1;
        }
    }
}

A. A

An3005

10 days ago

4.52ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for element in slice.iter_mut() {
        if *element % 2 == 0 {
            *element *= 2;  // Even numbers: double them
        } else {
            *element -= 1;  // Odd numbers: subtract 1
        }
    }
}

Pavel Bibichenko

erhoof

10 days ago

4.90ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for i in slice.iter_mut() {
        if *i % 2 == 0 {
            *i = *i * 2;
        }
        if (*i % 2 == 1) || (*i % 2 == -1) {
            *i -= 1;
        }
    }
}

Asrul Firdaus

AsrulF

10 days ago

8.40ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
        for num in slice.iter_mut() {
        if *num % 2 == 0 {
            *num *= 2
        } else {
            *num -= 1
        }
    }
}

TESTNETSOL

11 days ago

5.09ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for n in slice.iter_mut() {
        if *n % 2 == 0 {
            *n *= 2;
        } else {
            *n -= 1;
        }
    }
}

YE Qingtian

YE-Qingtian

11 days ago

13.78ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for (i, pointer) in slice.iter_mut().enumerate() {
        if *pointer%2 == 0{
            *pointer = *pointer * 2
        } else {
            *pointer -= 1
        }
    }
}

SubZ69

12 days ago

7.92ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    for i in slice.iter_mut() {
        match *i % 2 {
            0 => *i *= 2,
            _ => *i -= 1,
        }
    }
}

ASJ THILAK

ASJTHILAK

12 days ago

5.23ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    slice.iter_mut().for_each(|x| if *x%2 ==0 {*x *=2;} else{*x -=1;})
}

Kangyan-Zhou

13 days ago

4.37ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for i in slice.iter_mut() {
        if *i % 2 == 0 {
            *i *= 2;
        } else {
            *i -= 1;
        }
    }
}

Tamir Azaouag

Tamir-Azaouag

13 days ago

27.01ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate over the mutable slice and modify its elements.
    for num in slice.iter_mut(){
        if *num % 2 == 0{
            *num *= 2;
        }else{
            *num -= 1;
        }
    }
        
}

Alan Castro

acsoliz

14 days ago

6.13ms

89.23kb

pub fn transform_even_odd(slice: &mut [i32]) {
    // Your code here: iterate
    for num in slice.iter_mut(){
        if *num % 2 != 0 {
            *num -= 1;
        }else{
            *num *= 2;
        }
    } 
}