Яндекс.Блиц. Финал. А. Сапер

A_Miner.cs

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

namespace Yandex.Blitz
{
    class A_Miner
    {
        public static int solve(int n, int m, List<Tuple<int, int>> mines)
        {
            bool[][] x = new bool[n][];

            for (int i = 0; i < n; i++)
            {
                x[i] = new bool[m];
            }
            foreach (var mine in mines)
            {
                x[mine.Item1][mine.Item2] = true;
            }

            return rec(x, 0);
        }

        private static int rec(bool[][] x, int nstep)
        {
            int n = x.Length;
            int m = x[0].Length;

            int firstEmptyI = -1, firstEmptyJ = -1;
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < m; j++)
                {
                    if (!x[i][j])
                    {
                        firstEmptyI = i;
                        firstEmptyJ = j;
                        break;
                    }
                }
                if (-1 != firstEmptyI)
                {
                    break;
                }
            }

            if (-1 == firstEmptyI)
            {
                return nstep;
            }

            var next = new Stack<Tuple<int, int>>();
            next.Push(new Tuple<int, int>(firstEmptyI, firstEmptyJ));
            while (0 != next.Count)
            {
                var p = next.Pop();
                if (!check(x, p.Item1, p.Item2)) continue;
                x[p.Item1][p.Item2] = true;
                if (check(x, p.Item1 - 1, p.Item2))
                    next.Push(new Tuple<int, int>(p.Item1 - 1, p.Item2));
                if (check(x, p.Item1 + 1, p.Item2))
                    next.Push(new Tuple<int, int>(p.Item1 + 1, p.Item2));
                if (check(x, p.Item1, p.Item2 - 1))
                    next.Push(new Tuple<int, int>(p.Item1, p.Item2 - 1));
                if (check(x, p.Item1, p.Item2 + 1))
                    next.Push(new Tuple<int, int>(p.Item1, p.Item2 + 1));
            }

            return rec(x, nstep + 1);
        }

        private static bool check(bool[][] x, int i, int j)
        {
            int n = x.Length;
            int m = x[0].Length;
            return i < n && i >= 0 && j < m && j >= 0 && !x[i][j];
        }

        static void Main(string[] args)
        {
            var line = Console.ReadLine().Split(' ');
            int n = int.Parse(line[0]);
            int m = int.Parse(line[1]);

            if (n <= 0 || m <= 0)
            {
                Console.WriteLine(0);
                return;
            }

            int k = int.Parse(Console.ReadLine().Split(' ')[0]);
            if (k <= 0)
            {
                Console.WriteLine(1);
                return;
            }

            var mines = new List<Tuple<int, int>>();
            for (int i = 0; i < k; i++)
            {
                line = Console.ReadLine().Split(' ');
                mines.Add(new Tuple<int, int>(int.Parse(line[0]) - 1, int.Parse(line[1]) - 1));
            }

            int x = solve(n, m, mines);

            Console.WriteLine(x);
        }
    }
}