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<2) return false;
        for(int i=0;i<n;i++)
        {
            if(hmap.count(nums[i])&&i-hmap[nums[i]]<=k)
                return true;
            else
                hmap[nums[i]]=i;
            
        }
        return false;
    }
};