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：hashmap很简单。
public class Solution { public boolean containsNearbyDuplicate(int[] nums, int k) { Map<Integer,Integer> res=new HashMap<Integer,Integer>(); for(int i=0;i<nums.length;i++) { if(!res.containsKey(nums[i])) { res.put(nums[i],i); } else { if(i-res.get(nums[i])<=k) { return true; } else { res.put(nums[i],i); } } } return false; } }
原文：http://www.cnblogs.com/Machelsky/p/5874565.html