Find all k distant indices in an array

Array Two Pointers

77.4% acceptance

Feb 25, 2026

807

136

You are given a 0-indexed integer array nums and two integers key and k. A k-distant index is an index i of nums for which there exists at least one index j such that |i - j| <= k and nums[j] == key. Return a list of all k-distant indices sorted in increasing order.

Solution

Rust

Time O(n)

Space O(n)

LeetCode

solution.rs

impl Solution {
  pub fn find_k_distant_indices(nums: Vec<i32>, key: i32, k: i32) -> Vec<i32> {
    let n = nums.len() as i32;
    let mut result = Vec::new();
    let mut next = 0i32;
    for i in 0..n {
      if next > i { result.push(i); continue; }
      let lo = (i - k).max(0);
      let hi = (i + k).min(n - 1);
      if let Some(j) = (lo..=hi).find(|&j| nums[j as usize] == key) {
        next = j + k + 1;
        result.push(i);
      }
    }
    result
  }
}