LeetCode 1089. Duplicate Zeros

Problem Statement

impl Solution {
    pub fn duplicate_zeros(arr: &mut Vec<i32>) {
        let n = arr.len();
        let mut j = n;
        for i in 0..n {
            if arr[i] == 0 {
                j += 1;
            }
        }
        
        let mut i : i32 = (n  - 1) as i32;
        while i >= 0 {
            j -= 1;
            if j < n {
                arr[j] = arr[i as usize];
            }

            if arr[i as usize] == 0 {
                j-= 1;
                if j < n {
                    arr[j] = 0;
                }
            }
            i -= 1;
        }
    }
}