Java: Check if a sub-array is formed by consecutive integers from a given array of integers

Last update on April 07 2025 12:18:37 (UTC/GMT +8 hours)

Write a Java program to check if a sub-array is formed by consecutive integers from a given array of integers.

Example:
Input :
nums = { 2, 5, 0, 2, 1, 4, 3, 6, 1, 0 }
Output:
The largest sub-array is [1, 7]
Elements of the sub-array: 5 0 2 1 4 3 6

Sample Solution:

Java Code:

// Import necessary Java classes.
import java.lang.Math;
import java.util.Arrays;

// Define a class named 'solution'.
class solution
{
    // A method to check if the elements in a sub-array are consecutive.
    static boolean is_consecutive(int nums[], int i, int j, int min, int max)
    {
        if (max - min != j - i) {
            return false;
        }

        // Create a boolean array to check for duplicates.
        boolean check[] = new boolean[j - i + 1];

        // Check each element in the sub-array.
        for (int k = i; k <= j; k++)
        {
            if (check[nums[k] - min]) {
                return false;
            }

            check[nums[k] - min] = true;
        }

        return true;
    }
    
    // A method to find and print the largest consecutive sub-array.
    public static void find_Max_SubArray(int[] nums)
    {
        int len = 1;
        int start = 0, end = 0;

        for (int i = 0; i < nums.length - 1; i++)
        {
            int min_val = nums[i], max_val = nums[i];

            for (int j = i + 1; j < nums.length; j++)
            {
                min_val = Math.min(min_val, nums[j]);
                max_val = Math.max(max_val, nums[j]);

                // Check if the sub-array is consecutive and larger.
                if (is_consecutive(nums, i, j, min_val, max_val))
                {
                    if (len < max_val - min_val + 1)
                    {
                        len = max_val - min_val + 1;
                        start = i;
                        end = j;
                    }
                }
            }
        }

        // Print the largest sub-array and its elements.
        System.out.println("The largest sub-array is [" + start + ", " + end + "]");
        System.out.print("Elements of the sub-array: ");
        for (int x = start; x <= end; x++)
        {
            System.out.print(nums[x] + " ");			
        }
    }

    public static void main(String[] args)
    {
        int[] nums = { 2, 5, 0, 2, 1, 4, 3, 6, 1, 0 };
        System.out.println("Original array: " + Arrays.toString(nums));

        // Find and print the largest consecutive sub-array.
        find_Max_SubArray(nums);
    }
}

Sample Output:

                                                                            
Original array: [2, 5, 0, 2, 1, 4, 3, 6, 1, 0]
The largest sub-array is [1, 7]
Elements of the sub-array: 5 0 2 1 4 3 6 

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to find the longest subarray of consecutive integers in an unsorted array.
• Write a Java program to count the number of subarrays where all elements are consecutive integers.
• Write a Java program to find all subarrays that contain only consecutive even numbers.
• Write a Java program to check if a given subarray can be rearranged to form consecutive integers.

Java Code Editor:

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