MissingInteger 55%

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace algos
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] input = new int[] { 1, 3, 6, 4, 1, 2, -11 };
            solution(input);
        }

        public static int solution(int[] A)
        {
            var onlyPositiveValues = A.Where(x => x > 0).ToList();
            var candidate = 1;
            if (onlyPositiveValues.Any())
            {
                onlyPositiveValues.Sort();
                for (int i = 1; i < onlyPositiveValues.Count; i++)
                {
                    var previous = onlyPositiveValues[i-1];
                    var curr = onlyPositiveValues[i];
                    var diff = curr - previous;
                    if(diff > 1) // example 2 4
                    {
                       candidate = onlyPositiveValues[i - 1] + 1;
                       break;
                    }
                }

                return candidate;
            }
            else
            {
                return candidate;
            }

        }
    }
}