LeetCode 219: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 i and j is at most k.

此题在上一题Contains Duplicate的基础上，要求重复元素的半径不大于K。上题中，map中元素值为Key，元素索引下表为Value。所以在找到重复的情况下，可以判断下标差是否小于等于K。如果大于K，则修改已在map中元素对应的value，即下标。

class Solution {public:    bool containsNearbyDuplicate(vector<int>& nums, int k) {         map<int, int>int_map;         map<int,int>::iterator iter;        for (int i = 0; i<nums.size(); i++) {            if((iter=int_map.find(nums[i]) )!= int_map.end() ){                if (i - iter->second <= k) {                    return true;                }else{                    int_map.erase(iter);                }            }            int_map.insert(pair<int, int>(nums[i], i));        }        return false;    }};