LeetCode(43)-Contains Duplicate II

题目：

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 difference between i and j is at most k.

思路：

代码：

public class Solution {
public boolean containsNearbyDuplicate(int[] nums, int k) {
if(nums==null || nums.length<2) return false;
//key=int, val=index
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
for(int i=0; i<nums.length; i++) {
if(map.containsKey(nums[i])) {
int j = map.get(nums[i]);
if(i-j<=k) {return true;

}else{
map.remove(j);
map.put(nums[i], i);
}
} else {
map.put(nums[i], i);
}
}
return false;
}
}