C#: Checks how many integers are needed to complete the range

Last update on June 24 2025 12:57:39 (UTC/GMT +8 hours)

Complete Missing Numbers in Range

Write a C# program that accepts a list of integers and checks how many integers are needed to complete the range.

For example [1, 3, 4, 7, 9], between 1-9 -> 2, 5, 6, 8 are not present in the list. So output will be 4.

Sample Solution:

C# Sharp Code:

using System;

public class Example
{
    // Function to count the number of elements required to make an array consecutive
    public static int consecutive_array(int[] input_Array)
    {
        // Sorting the input array in ascending order
        Array.Sort(input_Array);

        // Counter variable to track the number of elements needed to make the array consecutive
        int ctr = 0;

        // Loop through the sorted array to calculate the number of elements needed to fill the gaps
        for (int i = 0; i < input_Array.Length - 1; i++)
        {
            // Increment the counter by the difference between adjacent elements minus 1
            // This calculates the number of missing elements between consecutive elements
            ctr += input_Array[i + 1] - input_Array[i] - 1;
        }

        // Return the count of elements needed to make the array consecutive
        return ctr;
    }

    // Main method to test the consecutive_array function
    public static void Main()
    {
        // Testing the consecutive_array function with different input arrays
        Console.WriteLine(consecutive_array(new int[] {1, 3, 5, 6, 9})); // Output: 2
        Console.WriteLine(consecutive_array(new int[] {0, 10})); // Output: 8
    }
}

Sample Output:

4
9

Flowchart:

For more Practice: Solve these Related Problems:

Write a C# program to return the list of missing integers in a sorted array without using built-in range functions.
Write a C# program to determine the longest sequence of missing numbers in an unsorted list.
Write a C# program to count how many numbers are missing in a custom range from min to max in the array.
Write a C# program to find the smallest and largest missing numbers in a given array.

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