TwoSumInput.java

import java.util.*;

public class TwoSumInput {
    public static int[] twoSum(int[] nums, int target) {
        HashMap<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            int complement = target - nums[i];
            if (map.containsKey(complement)) {
                return new int[] { map.get(complement), i };
            }
            map.put(nums[i], i);
        }
        return new int[0];
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter number of elements: ");
        int n = sc.nextInt();
        int[] nums = new int[n];
        System.out.println("Enter elements:");
        for (int i = 0; i < n; i++) {
            nums[i] = sc.nextInt();
        }
        System.out.print("Enter target: ");
        int target = sc.nextInt();
        int[] result = twoSum(nums, target);
        if (result.length == 2) {
            System.out.println("Indices: [" + result[0] + ", " + result[1] + "]");
        } else {
            System.out.println("No valid pair found.");
        }
    }
}