Leetcode 219. Contains Duplicate II

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.

标签 Array Hash Table

类似题目 (E) Contains Duplicate (M) Contains Duplicate III

 

 

 

思路：维持一个规模为k的移动窗口，对于新的元素，只要在移动窗口中可以找到相同的元素就返回true。

代码：

public class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        Set<Integer> hs = new HashSet<Integer>();
        for (int i = 0; i < nums.length; ++i) {
            if (hs.contains(nums[i])) return true;
            hs.add(nums[i]);
            if (i >= k) hs.remove(nums[i - k]);
        }
        return false;
    }
}