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

Luigi Terrone

LuigiTer

a day ago

4.75ms

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; 
        }
        else {
            *val -= 1; 
        }
        
    }
}

KuuShyn

2 days ago

4.76ms

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 {
        if *num % 2 == 0 {
            *num *= 2;
        }
        else {
            *num -= 1;
        }
    }
}

Moloson

2 days ago

4.34ms

89.23kb

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

Oleksandr Vechirko

alexvechirko

2 days ago

4.40ms

89.23kb

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

Heino Mortensen

hmortensen83

2 days ago

5.63ms

89.23kb

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

Karol Płatkowski

spoohie

3 days ago

6.03ms

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;
        }
    }
}

Camiam144

3 days ago

4.71ms

89.23kb

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

Camiam144

3 days ago

4.96ms

89.23kb

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

IwantHAPPINESS

3 days ago

5.64ms

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(|e| {
        if *e % 2 == 0 {
            *e *= 2;
        } else {
            *e -= 1;
        }
    });
}

IwantHAPPINESS

3 days ago

4.49ms

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(|e| {
        if *e % 2 == 0 {
            *e *= 2;
        } else {
            *e -= 1;
        }
    });
}

ydiarra

4 days ago

6.17ms

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(){
        match *i{
            n if (*i)%2 ==0 => *i = n*2,
            n => *i = n-1,
        }
    }
}

0x0f1

Paul4673

4 days ago

4.64ms

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 {
        if *element % 2 == 0 {
            *element *= 2;
        } else {
            *element -= 1;
        }
    }
}

0x0f1

Paul4673

4 days ago

4.18ms

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 {
        if *element % 2 == 0 {
            *element *= 2;
        } else {
            *element -= 1;
        }
    }
}

dattruongdev

5 days ago

4.23ms

89.23kb

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

Alexey Abramov

Mintstorm

5 days ago

6.47ms

89.23kb

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

Sarthak Mishra

sithtsar

5 days ago

4.93ms

89.23kb

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

Kr0wZ

6 days ago

5.76ms

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 *= 2;
        }
        else {
            *item -= 1; 
        } 
    }
}

DoughRing

7 days ago

4.04ms

89.23kb

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

BoΠeShΔdϴw³

B0neShAd0w

8 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 i in slice.iter_mut() {
        if *i %2 == 0 {
            *i = *i*2;
        } else {
            *i = *i-1;
        }
    }
}

Tri Nguyen

nguyentri

8 days ago

4.45ms

89.23kb

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

Lucop1911

9 days ago

9.21ms

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.iter_mut() {
        if *number%2 == 0 {
            *number *= 2;
        } else {
            *number -= 1;
        }
    }
}

Vivek Murali

Vivek-Murali

9 days ago

5.42ms

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(){
        match *i{
            n if (*i)%2 ==0 => *i = n*2,
            n => *i = n-1,
        }
    }
}

vanos001

9 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 i in slice.iter_mut(){
        *i = if (*i)%2 == 0 {
            2 * (*i)
        }else{
            *i - 1
        }
    }
}

Rocky.C

cloki0610

9 days ago

5.12ms

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 {
            return *x *= 2;
        }
        *x -= 1
    });
}

mojoshub

9 days ago

7.04ms

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 0..slice.len(){
        if slice[i] % 2 == 0{
            slice[i] *= 2
        }else{
            slice[i] -=  1
        }
    }
}

DragonFyre2k15

10 days ago

4.74ms

89.23kb

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

s.i

ssmi75

11 days ago

5.02ms

89.23kb

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

xxxxsk

11 days ago

6.26ms

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;
        }
    }
}

MysterOak

12 days ago

4.46ms

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(
            |num| {
                match *num % 2 {
                    0 => *num *= 2,
                    _ => *num -= 1
                }
            }
        );
}

megabyte

12 days ago

4.78ms

89.23kb

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

ikatlinsky

12 days ago

4.89ms

89.23kb

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

zzispp

12 days ago

4.62ms

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;
        }
    }
}

AndrewDane

13 days ago

4.04ms

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;
        }
    }
}

Enes

enesscevik

13 days ago

4.19ms

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 *= 2;
        }else {
            *s -= 1;
        }
    }
}

Abhishek Sharma

soro-kuraima

13 days ago

5.42ms

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;
        }
    }
}

hahu07

13 days ago

4.17ms

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;
        }
     }
}

Satya Sundar Sahu

satya200

13 days ago

5.19ms

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;
        }
    }
}

Thibault Guimbert

TGuimbert

13 days ago

4.59ms

89.23kb

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

Thibault Guimbert

TGuimbert

13 days ago

5.55ms

89.23kb

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

silaskoemen

14 days ago

3.93ms

89.23kb

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

Gomathi Shankar

gomathishankar37

14 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 i in slice.iter_mut() {
        if (*i)%2 == 0 {
            (*i) *= 2;
        }
        else {
            (*i) -= 1;
        }
    }
}

diucicd

14 days ago

4.11ms

89.23kb

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

Yaroslav

YarRoh

14 days ago

5.10ms

89.23kb

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

abelneo

abel-cod

15 days ago

4.73ms

89.23kb

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

Pierre Gordo

PierreGordo

15 days ago

3.94ms

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.iter_mut(){
        if *number%2 == 0{
            *number = *number * 2;
        }
        else{
            *number = *number - 1;
        }
    }
}

pudding64

15 days ago

6.52ms

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 = *val * 2;
        } else {
            *val = *val - 1;
        } 
    }
}

HusseinAbdelhamid

16 days ago

5.58ms

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 = *val * 2;
        }else{
            *val = *val -1;
        }
    }
}

Nicholas Chua

nicholaschuayunzhi

16 days ago

4.69ms

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 *= 2;
        } else {
            *s -= 1;
        }
    }
}

Issatay

kusetos

17 days ago

4.88ms

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{
        *num = match *num % 2{
            0 => *num * 2,
            _ => *num - 1,
        }
    }
}

Ushakov Andrey

stdstring

17 days ago

4.87ms

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;
        } else {
            *item = (*item) - 1;
        }
    }
}