2 time Find All Duplicates in an Array.cpp

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