Submission #311071

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Source Code Expand

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

class B1
{
    static void Main(string[] args)
    {
        string[] str = Console.ReadLine().Split(' ');
        int n = int.Parse(str[0]);
        int m = int.Parse(str[1]);
        int[] a = new int[m];
        int[] b = new int[m];
        for (int i = 0; i < m; i++)
        {
            string[] s = Console.ReadLine().Split(' ');
            a[i] = int.Parse(s[0]) - 1;
            b[i] = int.Parse(s[1]) - 1;
        }

        int need = 0;
        var searched = new List<int>(n);
        while (searched.Count < n)
        {
            int start = Enumerable.Range(0, n).Except(searched).First();
            var queue = new Queue<int>(n);
            queue.Enqueue(start);
            while (queue.Count > 0)
            {
                int node = queue.Dequeue();
                searched.Add(node);
                var next = IndexOf(a, node).Select(i => b[i]).Except(searched).Except(queue)
                    .Concat(IndexOf(b, node).Select(i => a[i]).Except(searched).Except(queue))
                    .Distinct();
                foreach (int index in next)
                {
                    queue.Enqueue(index);
                }
            }
            need++;
        }
        Console.WriteLine(need - 1);
        Console.ReadLine();
    }

    static IEnumerable<int> IndexOf(int[] array, int target)
    {
        for (int i = 0; i < array.Length; i++)
            if (array[i] == target) yield return i;
    }

}

Submission Info

Judge Result