4sum-Leetcode-AnujSoni.cpp

class Solution {
public:
    vector<vector<int>> fourSum(vector<int>& nums, int target) {
        vector<vector<int>> result;
        if (nums.size() == 0)
            return result;
        
        sort(nums.begin(), nums.end());
        
        for (int i = 0; i < nums.size(); i++){
            if (i > 0 && nums[i-1] == nums[i])
                continue;
            
            for (int j = i+1; j < nums.size(); j++){
                if (j > i+1 && nums[j] == nums[j-1])
                    continue;
                
                int start = j+1;
                int end = nums.size()-1;
                while (start < end){
                    int sum = nums[i] + nums[j] + nums[start] + nums[end];
                    if (sum == target){
                        result.push_back({nums[i], nums[j], nums[start], nums[end]});
                        while(start < end && nums[start] == nums[start+1]) start++;
                        while (start < end && nums[end] == nums[end-1]) end--;
						start++;
                        end--;
                    }
                    else if (sum > target)
                        end--;
                    else
                        start++;
                }
            }
        }
        
        return result;
    }
};