Leetcode NO.217 Contains Duplicate

本题题目要求如下：

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.

我的算法很直接，就是用hashset，遍历数组，如果该元素已经存在于hashset中，则是重复的，如果不在hashset中，则继续插入

class Solution {public:    bool containsDuplicate(vector<int>& nums) {        unordered_set<int> hashset;        for (int i = 0; i < nums.size(); ++i) {            if (hashset.find(nums[i]) != hashset.end()) {                return true;            }            else {                hashset.insert(nums[i]);            }        }        return false;    }};