I have an 2D array like this.
1 2 3
2 3 4
Are there anyway to find all the combination that meet the requirement below ?
I want to find all the combination such as each number from a column must be selected.
Such as
{1,2,3}
{1,2,4}
{1,3,3}
{1,3,4}
{2,2,3}
{2,2,4}
{2,3,3}
{2,3,4}
I have no idea how to generate all the combination like above.
Many thanks.
A typical method to create combinations is a recursive algorithm where you slice one element off each time and calculate combinations for the tail.
For example:
public static IEnumerable<IEnumerable<int>> Combinations (int[,] array, int column)
{
if (column == array.GetLength(1))
{
yield return Enumerable.Empty<int>();
yield break;
};
for(int j=0; j < array.GetLength(0); j++)
{
int v = array[j, column];
var first = new List<int>{ v };
foreach (var combination in Combinations(array, column+1))
{
yield return first.Concat(combination);
}
}
}
public static void Main()
{
int [,] a = new int [2,3] {
{1, 2, 3} ,
{2, 3, 4} ,
};
var result = Combinations(a, 0);
foreach (var t in result)
{
Console.WriteLine(string.Join(",", t));
}
}