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.

我的答案:

class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        Map<Integer, Integer> map = new HashMap<>();
		for (int i = 0; i < nums.length; i++) {
			Integer integer = map.get(nums[i]);
			if(integer == null){
				map.put(nums[i], i);
			}else{
				int value = i-integer;
				if(value<=k){
					return true;
				}
				map.put(nums[i], i);
			}
		}
		return false;
    }
}

大神的答案:

public boolean containsNearbyDuplicate(int[] nums, int k) {
        Set<Integer> set = new HashSet<Integer>();
        for(int i = 0; i < nums.length; i++){
            if(i > k) set.remove(nums[i-k-1]);
            if(!set.add(nums[i])) return true;
        }
        return false;
 }