4 sums.cpp

class Solution {
public:
    vector<vector<int>> fourSum(vector<int>& nums, int target) {
        vector<vector<int>> finalResult;
        int len = nums.size();
        if(len <= 3)
            return finalResult;
        else
            sort(nums.begin(), nums.end());
        
        for(int i = 0; i< len - 3;)
        {
            int a = nums[i];
            for(int j = i+1; j < len - 2;)
            {
                int b = nums[j];
                for(int p = j + 1, q = len-1; p < q;)
                {
                    int c = nums[p], d = nums[q];
                    int value = a + b + c + d;
                    if(value == target)
                    {
                        finalResult.push_back({a,b,c,d});  
                        while(d == nums[--q] );
                        while(c == nums[++p]);
                    }
                    else if(value > target){
                        while(d == nums[--q] );                       
                    }
                    else{
                        while(c == nums[++p]);
                    }        
                }
                j++;
                while(nums[j-1] == nums[j]&& j<len - 2)
                    j++;
            }
            i++;
            while(nums[i - 1] == nums[i] && i< len -3)
                i++;
        }
        return finalResult;
    }
};