4sum implementation in Java from leetcode

Question

The problem statement from leetcode says:

Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Fin

Answer 1

public ArrayList> fourSum(int[] num, int target) {
    Arrays.sort(num);
    ArrayList> res=new ArrayList>();
    int i=0;
    while(i t=new ArrayList();
                    t.add(num[i]);
                    t.add(num[j]);
                    t.add(num[left]);
                    t.add(num[right]);
                    res.add(t);
                    left++;
                    right--;
                    while(lefttarget-num[i]-num[j])
                    right--;
                else
                    left++;
            }
            j++;
            while(j