Question

How to check if a matrix columns contain numbers without repetition in C#

Answer 1

using System;
using System.Collections.Generic;

class Program
{
    static bool ColumnsHaveUniqueNumbers(int[,] matrix) {
        int rows = matrix.GetLength(0);
        int cols = matrix.GetLength(1);

        for (int j = 0; j < cols; j++) {
            HashSet<int> columnSet = new HashSet<int>();

            for (int i = 0; i < rows; i++) {
                if (!columnSet.Add(matrix[i, j])) { // If duplicate found
                    return false;
                }
            }
        }
        return true;
    }

    static void Main()
    {
        int[,] matrix1 = {
            {1, 4, 7},
            {2, 5, 8},
            {3, 6, 9}
        };

        int[,] matrix2 = {
            {1, 4, 7},
            {2, 4, 8},
            {3, 6, 9}
        };

        Console.WriteLine("Matrix 1 columns have unique numbers: " + ColumnsHaveUniqueNumbers(matrix1));
        Console.WriteLine("Matrix 2 columns have unique numbers: " + ColumnsHaveUniqueNumbers(matrix2));
    }
}



/*
run:

Matrix 1 columns have unique numbers: True
Matrix 2 columns have unique numbers: False

*/
 

 

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