Java: Get the index of the first number and the last number of a subarray

Last update on December 21 2024 09:34:04 (UTC/GMT +8 hours)

Subarray with Zero Sum

Write a Java program to get the index of the first and the last number of a subarray where the sum of numbers is zero. This is from a given array of integers.

Pictorial Presentation:

Sample Solution:

Java Code:

import java.util.*;

public class Solution {
    // Function to find the subarray with a sum of zero in the given array
    public static List<Integer> subarraySum(int[] nums) {
        List<Integer> temp = new ArrayList<>();
        
        // Check if the input array is null or empty, and return an empty list if so
        if (nums == null || nums.length == 0) {
            return temp;
        }
        
        int pre_Sum = 0;
        Map<Integer, Integer> map = new HashMap<>();
        map.put(pre_Sum, -1);
        
        // Iterate through the elements of the input array
        for (int i = 0; i < nums.length; i++) {
            pre_Sum += nums[i];
            
            // Check if the current prefix sum already exists in the map
            if (map.containsKey(pre_Sum)) {
                temp.add(map.get(pre_Sum) + 1); // Add the start index of the subarray
                temp.add(i); // Add the end index of the subarray
                return temp; // Return the list of indices
            }
            
            // If the prefix sum is not found, add it to the map with its index
            map.put(pre_Sum, i);
        }
        
        return temp; // Return an empty list if no subarray with a sum of zero is found
    }
    
    public static void main(String[] args) {
        int[] nums = {1, 2, 3, -6, 5, 4};

        // Print the original array and the indices of the subarray with a sum of zero
        System.out.println("Original Array: " + Arrays.toString(nums));
        System.out.println("Index of the subarray of the said array where the sum of numbers is zero: " + subarraySum(nums));
    }		
}

Sample Output:

Original Array : [1, 2, 3, -6, 5, 4]
Index of the subarray of the said array where the sum of numbers is zero: [0, 3]

Flowchart:

Java Code Editor:

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