Java: Find contiguous subarray within a given array of integers which has the largest sum

Last update on December 21 2024 09:33:31 (UTC/GMT +8 hours)

Write a Java program to find a contiguous subarray within a given array of integers with the largest sum.

In computer science, the maximum sum subarray problem is the task of finding a contiguous subarray with the largest sum, within a given one-dimensional array A[1...n] of numbers. Formally, the task is to find indices and with, such that the sum is as large as possible.

Example:
Input :
int[] A = {1, 2, -3, -4, 0, 6, 7, 8, 9}
Output:
The largest sum of contiguous sub-array: 30

Sample Solution:

Java Code:

// Import the necessary Java class.
import java.util.Arrays;

// Define a class named 'solution'.
class solution {
    // Method to find the largest sum of a contiguous sub-array.
    public static int largest_sum(int[] A) {
        // Initialize variables for maximum element value and maximum ending here.
        int max_ele_val = 0;
        int max_end = 0;

        // Iterate through the elements in array 'A'.
        for (int i : A) {
            max_end = max_end + i;

            // Ensure that 'max_end' doesn't go below zero.
            max_end = Integer.max(max_end, 0);

            // Update 'max_ele_val' with the maximum value.
            max_ele_val = Integer.max(max_ele_val, max_end);
        }
        return max_ele_val;
    }

    // Main method to demonstrate finding the largest sum of a contiguous sub-array.
    public static void main(String[] args) {
        // Initialize an array.
        int[] A = {1, 2, -3, -4, 0, 6, 7, 8, 9};
        System.out.println("\nOriginal array: " + Arrays.toString(A));

        // Call the 'largest_sum' method to find and print the largest sum.
        System.out.println("The largest sum of a contiguous sub-array: " + largest_sum(A));
    }
} 

Sample Output:

Original array: [1, 2, -3, -4, 0, 6, 7, 8, 9]
The largest sum of contiguous sub-array: 30

Flowchart:

Java Code Editor:

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