3sum

threeSum.java

package others;

import java.util.Arrays;
import java.util.ArrayList;

public class threeSum {
    public static void main(String args[]) {
        int arr[] = {-7 , 8, 9, 2 , -3, -5, 3, 2, 5, 1, 2, -4};
        System.out.println(getThreeSum(arr));
    }

    public static ArrayList<ArrayList<Integer>> getThreeSum(int[] num) {
        Arrays.sort(num);
        if (num.length < 3) {
            return null;
        }
        ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
        for (int k = 0; k <= num.length - 3; k++) {
            int i = k + 1;
            int j = num.length - 1;
            while (i < j) {
                int sum = num[i] + num[j] + num[k];
                if (sum == 0) {
                    ArrayList<Integer> list = new ArrayList<Integer>();
                    list.add(num[k]);
                    list.add(num[i]);
                    list.add(num[j]);
                    result.add(list);
                    i++;
                    j--;
                    
                } else if (sum < 0) {
                    i++;
                } else {
                    j--;
                }
            }
        }
        return result;

    }
}