competitive-programming-lib 0.1.0

pub fn merge_sort(arr: &mut [i32]) {
    let len = arr.len();
    if len <= 1 {
        return;
    }

    let mid = len / 2;
    merge_sort(&mut arr[..mid]);
    merge_sort(&mut arr[mid..]);
    merge(arr, mid);
}

fn merge(arr: &mut [i32], mid: usize) {
    let mut left = arr[..mid].to_vec();
    let mut right = arr[mid..].to_vec();

    let (mut i, mut j, mut k) = (0, 0, 0);
    while i < left.len() && j < right.len() {
        if left[i] <= right[j] {
            arr[k] = left[i];
            i += 1;
        } else {
            arr[k] = right[j];
            j += 1;
        }
        k += 1;
    }

    while i < left.len() {
        arr[k] = left[i];
        i += 1;
        k += 1;
    }

    while j < right.len() {
        arr[k] = right[j];
        j += 1;
        k += 1;
    }
}