multiplication problem two-dimensional array per number

Question

Given two dimensional array of size n×n. Get new array by multiplying the elements of each row of the first array by the largest from the values ​​of the elements of the corresponding row of the second array.

First Array:
2 3 4
1 1 1
12 1 1
Second Array:
8 12 16
1 1 1
12 1 1

I tried to get this result, but I have some problem.

using System;

namespace Lab_4
{
    internal class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Введите размерность массива - n:");
            int n = Convert.ToInt32(Console.ReadLine());
            int[,] array = new int[n, n];
            int[,] A = new int[n, n];
            int max,i,j;
            max = 999;
            Random r = new Random();
            for (i = 0; i < n; i++)
            {
                for (j = 0; j < n; j++)
                {
                    array[i, j] = r.Next(1, 10);
                }
            }
            Console.WriteLine("Ваш массив:");
            for (i = 0; i < n; i++)
            {
                for (j = 0; j < n; j++)
                {
                    Console.Write(array[i, j] + " ");
                }
                Console.WriteLine();
            }
            for (i = 0; i < n; i++)
            {
                for (j = 0; j < n - 1; j++)
                {
                    max = array[i, j];
                    if (max < array[i, j + 1])
                    {
                        max = array[i, j];
                    }
                }
                A[i, j] = array[i, j] * max;
            }
            Console.WriteLine("Новый массив :");
            for (i = 0; i < n; i++)
            {
                for (j = 0; j < n; j++)
                {
                    Console.Write(A[i, j] + " ");
                }
                Console.WriteLine();
            }
        }
    }
}

Answer 1

I'd break up your program into pieces to make it easier to follow:

  static void Main(string[] args)
  {
    Console.WriteLine("Введите размерность массива - n:");
    int n = Convert.ToInt32(Console.ReadLine());
    int[,] array = new int[n, n];
    int[,] A = new int[n, n];
    int max,i,j;
    max = 999;
    Random r = new Random();
    for (i = 0; i < n; i++)
    {
        for (j = 0; j < n; j++)
        {
            array[i, j] = r.Next(1, 10);
        }
    }
  
    Console.WriteLine("Ваш массив:");
    displayArray(array, "0");
  
    for (i = 0; i < n; i++)
    {
      int rowMax = getRowMax(array, i);
      for (j = 0; j < n; j++)
      {
        A[i, j] = array[i, j] * rowMax;
      }
    }
    
    Console.WriteLine("Новый массив :");
    displayArray(A, "00");
  }

  public static void displayArray(int[,] arr, String format) {
    for(int row=0; row<=arr.GetUpperBound(0); row++) {
      for(int col=0; col<=arr.GetUpperBound(1); col++) {
        Console.Write(arr[row, col].ToString(format) + " ");
      }
      Console.WriteLine();
    }
  }
  
  public static int getRowMax(int[,] arr, int row) {
    int max = arr[row, 0];
    for(int col=1; col<=arr.GetUpperBound(1); col++) {
      if (arr[row, col] > max) {
        max = arr[row, col];
      }
    }
    return max;
  }

Sample run:

Введите размерность массива - n:
10
Ваш массив:
3 3 8 3 2 4 2 7 8 1 
6 3 7 9 5 7 4 8 5 8 
7 5 7 6 5 6 1 3 5 3 
6 3 8 3 2 8 3 4 2 3 
8 1 6 4 8 8 4 2 1 2 
9 7 8 8 3 8 4 2 8 5 
6 9 9 7 6 9 8 5 8 7 
3 5 6 7 6 3 5 3 9 2 
7 7 1 6 9 9 5 3 8 4 
4 6 5 6 9 2 1 9 7 6 
Новый массив :
24 24 64 24 16 32 16 56 64 08 
54 27 63 81 45 63 36 72 45 72 
49 35 49 42 35 42 07 21 35 21 
48 24 64 24 16 64 24 32 16 24 
64 08 48 32 64 64 32 16 08 16 
81 63 72 72 27 72 36 18 72 45 
54 81 81 63 54 81 72 45 72 63 
27 45 54 63 54 27 45 27 81 18 
63 63 09 54 81 81 45 27 72 36 
36 54 45 54 81 18 09 81 63 54