Contains Duplicate II

##题目

####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 i and j is at most k.

##解题思路
这道题是Contains Duplicate的扩展,但是思路依然很简单,只是判断是否存在两个重复的数字之间的索引间隔是否不大于K。对于HashMap而言,其中key为数字,value为该数组所有的数组中的索引。

##算法代码
代码采用JAVA实现:

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public class Solution {
public boolean containsNearbyDuplicate(int[] nums, int k) {
if(nums==null || nums.length==0) return false;
HashMap<Integer,Integer> map=new HashMap<Integer,Integer>();
//其中key为数值,value为其索引位置
for(int i=0;i<nums.length;i++)
{
if(map.containsKey(nums[i]))
{
int j=map.get(nums[i]);
//只需要判断间隔是否不大于K
if(i-j<=k) return true;

}
map.put(nums[i],i);
}
return false;
}
}

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