leetcode 219 Contains Duplicate II C++

用hash的方法很快

class Solution {public:    bool containsNearbyDuplicate(vector<int>& nums, int k) {        unordered_map<int,int> maps;        for(int i=0 ;i < nums.size(); i++){            if(maps.count(nums[i])){                if(i-maps[nums[i]] <= k){                    return true;                }            }            maps[nums[i]] = i;        }        return false;    }};