https://leetcode.com/problems/contains-duplicate-ii/
Given an array of integers and an integer k, find out whether there there are two distinct indices i and j in the array such that nums[i] = nums[j] and the difference between iand j is at most k.
解题思路：
简单的新题，在前题 Contains Duplicate 的基础上，用map来记录数字对应的index。遇到map中有的数字就去比较他们的下标，小于等于k就返回true，否则更新下标。
public class Solution { public boolean containsNearbyDuplicate(int[] nums, int k) { Map<Integer, Integer> map = new HashMap<Integer, Integer>(); for(int i = 0; i < nums.length; i++) { if(map.containsKey(nums[i])) { if(i - map.get(nums[i]) <= k) { return true; } } map.put(nums[i], i); } return false; } }
原文：http://www.cnblogs.com/NickyYe/p/4555752.html