Duplicate zeros

Array Two Pointers

53.4% acceptance

Feb 25, 2026

2828

795

Given a fixed-length integer array arr, duplicate each occurrence of zero, shifting the remaining elements to the right. Note that elements beyond the length of the original array are not written. Do the above modifications to the input array in place and do not return anything.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn duplicate_zeros(arr: &mut Vec<i32>) {
    let n = arr.len();
    let zeros = arr.iter().filter(|&&x| x == 0).count();
    let mut i = n as i32 - 1;
    let mut j = (n + zeros) as i32 - 1;
    while i >= 0 {
      if arr[i as usize] == 0 {
        if j < n as i32 { arr[j as usize] = 0; }
        j -= 1;
        if j < n as i32 { arr[j as usize] = 0; }
      } else {
        if j < n as i32 { arr[j as usize] = arr[i as usize]; }
      }
      i -= 1;
      j -= 1;
    }
  }
}