Contains Duplicate

 https://leetcode.com/problems/contains-duplicate/

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

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