Leetcode 219. Contains Duplicate II

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.

217的升级版，http://blog.csdn.net/accepthjp/article/details/65442908

要求判断是否存在重复的数之间的下标距离不超过k。

出现过的数和之前的下标求绝对值，超过K则放弃前面的下标，记录新下标。

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