LeetCode-in-Java

2200. Find All K-Distant Indices in an Array

Easy

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.

Example 1:

Input: nums = [3,4,9,1,3,9,5], key = 9, k = 1

Output: [1,2,3,4,5,6]

Explanation: Here, nums[2] == key and nums[5] == key.

• For index 0, |0 - 2| > k and |0 - 5| > k, so there is no j where |0 - j| <= k and nums[j] == key. Thus, 0 is not a k-distant index.

• For index 1, |1 - 2| <= k and nums[2] == key, so 1 is a k-distant index.

• For index 2, |2 - 2| <= k and nums[2] == key, so 2 is a k-distant index.

• For index 3, |3 - 2| <= k and nums[2] == key, so 3 is a k-distant index.

• For index 4, |4 - 5| <= k and nums[5] == key, so 4 is a k-distant index.

• For index 5, |5 - 5| <= k and nums[5] == key, so 5 is a k-distant index.

• For index 6, |6 - 5| <= k and nums[5] == key, so 6 is a k-distant index.

Thus, we return [1,2,3,4,5,6] which is sorted in increasing order.

Example 2:

Input: nums = [2,2,2,2,2], key = 2, k = 2

Output: [0,1,2,3,4]

Explanation: For all indices i in nums, there exists some index j such that |i - j| <= k and nums[j] == key, so every index is a k-distant index.

Hence, we return [0,1,2,3,4].

Constraints:

• 1 <= nums.length <= 1000
• 1 <= nums[i] <= 1000
• key is an integer from the array nums.
• 1 <= k <= nums.length

Solution

import java.util.ArrayList;
import java.util.List;

public class Solution {
    public List<Integer> findKDistantIndices(int[] nums, int key, int k) {
        List<Integer> ans = new ArrayList<>();
        int start = 0;
        int n = nums.length;
        for (int i = 0; i < n; i++) {
            if (nums[i] == key) {
                start = Math.max(i - k, start);
                int end = Math.min(i + k, n - 1);
                while (start <= end) {
                    ans.add(start++);
                }
            }
        }
        return ans;
    }
}

This site is open source. Improve this page.