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.

不能动态维护k+1大小的map，因为若有相同元素，删除元素时会将新加入的相同大小的元素删掉，导致错误。

 class Solution {
 public:
     bool containsNearbyDuplicate(vector<int>& nums, int k) {
         map<int,int> hmap;
         int n=nums.size();
         if(n<) return false;
         for(int i=;i<n;i++)
         {
             if(hmap.count(nums[i])&&i-hmap[nums[i]]<=k)
                 return true;
             else
                 hmap[nums[i]]=i;

         }
         return false;
     }
 };