15算法课程 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.

solution:

hash表

code:

class Solution {public:    bool containsNearbyDuplicate(vector<int>& nums, int k) {        unordered_map<int, int> hash;        for(int i = 0; i < nums.size(); i++)        {            if(i > k) hash[nums[i-k-1]]--;            if(hash[nums[i]] > 0) return true;            hash[nums[i]]++;        }        return false;    }};