c # 编程题，会的直接留下代码，感谢

Question

Write a program that examines a square matrix of integers with dimensions N x N. The first input line contains the matrix size N, and the rows of the matrix follow on successive input lines. All numbers in each row will be separated by a single space.

Determine how many matrix columns contain a permutation of the numbers 1, 2, ..., N (i.e. each of the numbers 1, 2, ..., N appears exactly once in the column). Write this number to the output.

Note: N may be as large as 1,000. If your program runs in O(N^3), it will be too slow to pass all the tests.

Example:

Input:

5  
1 1 3 4 5  
2 2 3 1 5  
4 3 5 5 1
12 4 23 2 3  
5 5 3 3 2

Output:

2

Answer 1

 

 

using System;

namespace Test
{
    class Program
    {
        private static void GetMinMax(int[] arr, out int min, out int max)
        {
            min = max = arr[0];
            int n = arr.Length;
            for (var i = 0; i < n; i++)
            {
                if (min > arr[i]) min = arr[i];
                if (max < arr[i]) max = arr[i];
            }
        }
        private static bool isConsecutive(int[] arr)
        {
            var n = arr.Length;
            int min, max;
            GetMinMax(arr, out min, out max);
            if (max - min + 1 == n)
            {
                int i,j;
                for (i = 0; i < n; i++)
                {
                    if (arr[i] < 0) j = -arr[i] - min; else j = arr[i] - min;
                    if (arr[j] > 0) arr[j] = -arr[j]; else return false;
                }

                return true;
            }
            return false;
        }
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            var arr = new int[n][];
            for (var i = 0; i < arr.Length; i++) arr[i] = new int[n];

            for (int i = 0; i < n; i++)
            {
                var item = Console.ReadLine().Split(' ');
                for (var j = 0; j < item.Length&&j<n; j++)
                {
                    arr[j][i] = int.Parse(item[j]);
                }
            }
            int count = 0;
            for (var i = 0; i < n; i++) {
                if (isConsecutive(arr[i])) count++;
            }
            Console.Write(count);
           
        }
    }

}