C#: Smallest positive which is not present in an array

C# Sharp Array: Exercise-40 with Solution

Write a C# Sharp program that takes an array of integers and finds the smallest positive integer that is not present in that array.

Sample Data:
({ 1,2,3,5,6,7}) -> 4
({-1, -2, 0, 1, 3, 4, 5, 6}) -> 2

Sample Solution:

C# Sharp Code:

using System;
using System.Linq;

namespace exercises
{
    class Program
    {
        static void Main(string[] args)
        {
            // Initializing an array of integers
            int[] nums1 = { 1, 2, 3, 5, 6, 7 };

            // Displaying original array elements using string.Join method
            Console.WriteLine("Original array elements:");
            Console.WriteLine($"{string.Join(", ", nums1)}");

            // Finding and displaying the smallest positive number not present in the array
            Console.WriteLine("Smallest positive number which is not present in an array: " + test(nums1));

            // Creating another array of integers
            int[] nums2 = { -1, -2, 0, 1, 3, 4, 5, 6 };
            Console.WriteLine("\nOriginal array elements:");
            Console.WriteLine($"{string.Join(", ", nums2)}");

            // Finding and displaying the smallest positive number not present in the second array
            Console.WriteLine("Smallest positive number which is not present in an array: " + test(nums2));
        }

        // Method to find the smallest positive number not present in the array
        public static int test(int[] nums)
        {
            int i = 1;

            // Loop until the smallest positive number not present in the array is found
            while (true)
            {
                // Check if the current value of 'i' is not present in the array
                if (!(nums.Count(v => v == i) > 0))
                {
                    // If 'i' is not present in the array, return it as the smallest positive number
                    return i;
                }
                // Increment 'i' to check the next positive number
                i++;
            }
        }
    }
}

Sample Output:

Original array elements:
1, 2, 3, 5, 6, 7
Smallest positive which is not present in an array: 4

Original array elements:
-1, -2, 0, 1, 3, 4, 5, 6
Smallest positive which is not present in an array: 2
 

Flowchart:

C# Sharp Code Editor:

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