217 Contains Duplicate

链接：https://leetcode.com/problems/contains-duplicate/
问题描述：
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.

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如果给出数组中有重复元素则返回true否则返回false；

class Solution {public:    bool containsDuplicate(vector<int>& nums) {        map<int,int> hm;        for(int i=0;i<nums.size();i++)        {            if(hm.find(nums[i])!=hm.end())                return true;            hm[nums[i]]=1;        }        return false;    }};