Java [Leetcode 219]Contains Duplicate II

题目描述：

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.

解题思路：

HashMap解决。

代码如下：

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