Leetcode 219 Contains Duplicate II STL

 1 class Solution {
 2 public:
 3     bool containsNearbyDuplicate(vector<int>& nums, int k) {
 4         map<int,int> mii;
 5         for (int i = 0;i<nums.size() ;++i)
 6         {
 7             if (mii.find(nums[i]) != mii.end()) 
 8             {
 9                 if(i - mii[nums[i]] <= k) return true;
10             }
11             mii[nums[i]] = i;
12         }
13         return false;
14     }
15 };