LeetCode 18. 4Sum

// C++
vector<vector<int>> fourSum(vector<int>& nums, int target) 
{
	sort(nums.begin(), nums.end());
	vector<vector<int>>result;
	for (int i = 0; i < nums.size(); i++)
	{
		for (int j = i+1; j < nums.size()-1; j++)
		{
			if ((i > 0) && nums[i] == nums[i - 1]) continue;
			if ((j!=i+1)&& nums[j] == nums[j - 1]) continue;
			int l = j + 1; int r = nums.size() - 1;
			while (l<r)
			{
				
				int k = nums[i] + nums[j] + nums[l] + nums[r];
				
				if (k > target) r--;
				if (k < target) l++;
				if (k == target) 
				{ 
					result.push_back(vector<int>{ nums[i], nums[j], nums[l], nums[r] });
					while (l < (nums.size() - 1) && (nums[l] == nums[l + 1])) l++;
					while (r > l && (nums[r] == nums[r - 1])) r--;
					l++; r--;
				}
			}
		}
	}
	return result;
}

//Java

class Solution {
    public List<List<Integer>> fourSum(int[] nums, int target) {
        List<List<Integer>> ans=new ArrayList<>();
        Arrays.sort(nums);
        for(int i=0;i<nums.length;i++)
        {
            for(int j=i+1;j<nums.length;j++)
            {
                for(int m=j+1;m<nums.length;m++)
                {
                    for(int n=m+1;n<nums.length;n++)
                    {
                        int a=nums[i]+nums[j]+nums[m]+nums[n];
                        if(a==target) {
                            int k=0;
                            for(k=0;k<ans.size();k++)
                            {
                                if(ans.get(k).equals(Arrays.asList(nums[i], nums[j], nums[m], nums[n])))
                                {
                                   break;
                                }
                            }
                            if(k==ans.size()){
                                ans.add(Arrays.asList(nums[i], nums[j], nums[m], nums[n]));
                            }
                            if(a>target)
                            {
                                break;
                            }
                        }
                    }
                }
            }
        }
        return ans;
    }
}