Question

How to rearrange an array into a zig-zag pattern (a < b > c < d > e < f > g) in Rust

Answer 1

// This program rearranges an array into a zig-zag pattern, where the elements 
// alternate between being smaller and larger than their neighbors

// a < b > c < d > e < f > g...
// 3 < 5 > 1 < 9 > 6 < 7 > 2 < 4

fn rearrange_into_zigzag(arr: &mut [i32]) {
    for i in 0..arr.len().saturating_sub(1) {
        if i % 2 == 0 {
            // Expect arr[i] < arr[i + 1]
            if arr[i] > arr[i + 1] {
                arr.swap(i, i + 1);
            }
        } else {
            // Expect arr[i] > arr[i + 1]
            if arr[i] < arr[i + 1] {
                arr.swap(i, i + 1);
            }
        }
    }
}

fn main() {
    let mut arr = [3, 5, 1, 7, 9, 6, 4, 2];

    rearrange_into_zigzag(&mut arr);

    println!("{arr:?}");
}

    
/*
run:

[3, 5, 1, 9, 6, 7, 2, 4]

*/

 

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Answer 2

// This program rearranges an array into a zig-zag pattern, where the elements 
// alternate between being smaller and larger than their neighbors

// a < b > c < d > e < f > g...
// 3 < 5 > 1 < 9 > 6 < 7 > 2 < 4
    
fn rearrange_into_zigzag(arr: &mut [i32]) {
    for i in 0..arr.len().saturating_sub(1) {
        let should_swap =
            (i % 2 == 0 && arr[i] > arr[i + 1]) ||
            (i % 2 == 1 && arr[i] < arr[i + 1]);

        if should_swap {
            arr.swap(i, i + 1);
        }
    }
}

fn main() {
    let mut arr = [3, 5, 1, 7, 9, 6, 4, 2];

    rearrange_into_zigzag(&mut arr);

    println!("{arr:?}");
}

    
/*
run:

[3, 5, 1, 9, 6, 7, 2, 4]

*/

 

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