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

Smith, Taylor

a647965_fidelity

2 hours ago

4.09ms

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;
        }
    }
}

jh4vision

12 hours ago

7.13ms

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;
        }
    }
}

jh4vision

12 hours ago

5.32ms

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;
        }
    }
}

Zisraw

a day 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.
    slice.iter_mut().for_each(|x| 
        if *x % 2 == 0 {
            *x *= 2;
        }
        else{
            *x -= 1;
        }
    );
}

Selim Gökmen

sgoekmen

a day 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 s in slice {
        if *s % 2 == 0 {
            *s *= 2;
        } else {
            *s -= 1;
        }
    }
}

Francisco Alejandro

francisco-alejandro

a day ago

4.60ms

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;
        }
        
    }
}

Vitalol

a day ago

4.15ms

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
        }
    }
}

zhanglonghu

a day ago

4.59ms

89.23kb

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

greg95000

2 days ago

5.51ms

89.23kb

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

Dani-Drk

2 days ago

3.79ms

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;
        }
    });
}

AndrewNice

2 days ago

4.07ms

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;
        }
    }
}

AyotuntosimiLoye

3 days ago

4.53ms

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;
        }
    }
}

noname

random1106

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

Christophe Mohimont

mohic

3 days ago

5.56ms

89.23kb

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

Yury

Just-Captain

3 days ago

5.51ms

89.23kb

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

Theepakorn Phayonrat

Pottarr

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.
    slice.iter_mut().for_each(|x| {
        if *x % 2 == 0 {
            *x *= 2;
        } else {
            *x -= 1;
        }
    });
}

slime21023

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

Muhammad Rizki Rijal

eezhal92

4 days ago

4.13ms

89.23kb

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

Chris Hendley

chhendley

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

JIA

bytesxz

4 days ago

5.30ms

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

idorocodes

4 days ago

4.79ms

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 = *element * 2
        } else {
            *element = *element - 1
        }
    }
}

idorocodes

4 days ago

4.32ms

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 = *element * 2
        } else {
            *element = *element - 1
        }
    }
}

mickaelactel

4 days ago

4.20ms

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 = *element * 2
        } else {
            *element = *element - 1
        }
    }
}

mickaelactel

4 days ago

4.05ms

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 = *element * 2
        } else {
            *element = *element - 1
        }
    }
}

amdfxlucas

6 days ago

5.61ms

89.23kb

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

lzpeng

liuzhanpeng

7 days ago

5.24ms

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;
        }
    });
}

Cao Việt Anh

vanhcao3

7 days ago

4.25ms

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;
        }
    })
}

PikachuMJ

7 days ago

4.76ms

89.23kb

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

Paolo Deidda

DePoli97

7 days ago

4.93ms

89.23kb

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

firefly

KamisAyaka

7 days ago

6.16ms

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;
        }
    }
}

amir lavasani

HumaneLogic

7 days ago

4.42ms

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

Aryan Singh

aryan0078

8 days ago

4.09ms

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
    }
   }
}

Solange

SolangeLL

8 days ago

4.18ms

89.23kb

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

ggalliot

lepolpierre

8 days ago

4.03ms

89.23kb

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

0xdangit

8 days ago

6.01ms

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;
        }
    }
}

0xdangit

8 days ago

5.31ms

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

Heorhii

Kagev

9 days ago

4.53ms

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;
        }
    }
}

Heorhii

Kagev

9 days ago

4.25ms

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;
        }
    }
}

Javier Romario

Javier-Romario

9 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 {
        if *num % 2 == 0 {
            *num *= 2;        // Even: double it
        } else {
            *num -= 1;        // Odd: subtract 1
        }
    }
}

Varun D

varun-d

9 days ago

4.25ms

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 -=1;
        }
    } 
}

P S

psvr

9 days ago

4.25ms

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().map(|x| if *x % 2 == 0 {*x = *x * 2} else {*x = *x - 1}).collect()
    for item in slice.iter_mut() {
        if *item % 2 == 0 {
            *item *= 2; 
        } else {
            *item -= 1;
        }
    }
}

Aruzal

10 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.
    for element in slice.iter_mut() {
        if *element % 2 == 0 {
            *element = *element * 2;
        } else {
            *element = *element - 1;
        }
    }
}

JD

arukanoido

10 days ago

4.03ms

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;
        }
    }
}

rlsh74

10 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() {
        if *n % 2 == 0 {
            *n *= 2;
        } else {
            *n -= 1;
        }
    }
}

Akira

itsmewayne

10 days ago

4.80ms

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;
        }
    }
}

Phong H.

doivjpxx

10 days ago

4.47ms

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;
        }
    }
}

Victor Augusto Ferreira

Auguxto

11 days ago

4.41ms

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;
        }
    }
}

DBrouillet

11 days ago

6.41ms

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
        }
    }
}

ashishkr2912

11 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 i in slice{
        if *i%2==0{
            *i= *i * 2;
        }else if *i%2!=0{
            *i=*i-1
        }
    }
}

Phan Nam

PhanNam1501

11 days ago

5.39ms

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;
        }
    }
}