FourElementWithSum.java

import java.util.*;

class FourElementWithSum {

	public static void fourSum(int X, int[] arr,
							Map<Integer, pair> map)
	{
		int[] temp = new int[arr.length];

		for (int i = 0; i < temp.length; i++)
			temp[i] = 0;

		for (int i = 0; i < arr.length - 1; i++) {

			for (int j = i + 1; j < arr.length; j++) {

				int curr_sum = arr[i] + arr[j];

				if (map.containsKey(X - curr_sum)) {

					pair p = map.get(X - curr_sum);

					if (p.first != i && p.sec != i
						&& p.first != j && p.sec != j
						&& temp[p.first] == 0
						&& temp[p.sec] == 0 && temp[i] == 0
						&& temp[j] == 0) {

						System.out.printf(
							"%d,%d,%d,%d", arr[i], arr[j],
							arr[p.first], arr[p.sec]);
						temp[p.sec] = 1;
						temp[i] = 1;
						temp[j] = 1;
						break;
					}
				}
			}
		}
	}

	public static Map<Integer, pair> twoSum(int[] nums)
	{
		Map<Integer, pair> map = new HashMap<>();
		for (int i = 0; i < nums.length - 1; i++) {
			for (int j = i + 1; j < nums.length; j++) {
				map.put(nums[i] + nums[j], new pair(i, j));
			}
		}
		return map;
	}

	public static class pair {
		int first, sec;

		public pair(int first, int sec)
		{
			this.first = first;
			this.sec = sec;
		}
	}

	public static void main(String args[])
	{
		int[] arr = { 10, 20, 30, 40, 1, 2 };
		int n = arr.length;
		int X = 91;
		Map<Integer, pair> map = twoSum(arr);

		fourSum(X, arr, map);
	}
}