leetcode講解--217. Contains Duplicate

217. Contains Duplicate

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

so easy的一道題。我直接上代碼吧：

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        unordered_map<int, int> hash;
        for(auto i:nums){
            hash[i]++;
        }
        for(auto i:hash){
            if(i.second>=2)
                return true;
        }
        return false;
    }
};