Producto cartesiano de dos conjuntos

Sean A y B dos conjuntos, el producto cartesiano A × B es el conjunto de todos los pares ordenados de elementos de A y B 
A × B = {{x, y} : x ∈ A, y ∈ B}
 

Sean A = {a, b, c} y B = {d, e, f} 
El producto cartesiano de dos conjuntos es 
A x B = {a, d}, {a, e}, {a, f}, { b, d}, {b, e}, {b, f}, {c, d}, {c, e}, {c, f}}
A tiene 3 elementos y B también tiene 3 elementos. El Producto Cartesiano tiene 3 x 3 = 9 elementos.
En general, si hay m elementos en el conjunto A y n elementos en B, el número de elementos en el Producto Cartesiano es mxn

 
Dados dos conjuntos finitos no vacíos, escriba un programa para imprimir el producto cartesiano. 
Ejemplos: 
 

Input : A = {1, 2}, B = {3, 4}
Output : A × B = {{1, 3}, {1, 4}, {2, 3}, {2, 4}}

Input  : A = {1, 2, 3} B = {4, 5, 6}
Output : A × B = {{1, 4}, {1, 5}, {1, 6}, {2, 4}, 
         {2, 5}, {2, 6}, {3, 4}, {3, 5}, {3, 6}}

// C++ Program to find the Cartesian Product of Two Sets
#include <stdio.h>
 
void findCart(int arr1[], int arr2[], int n, int n1)
{
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n1; j++)
            printf("{%d, %d}, ", arr1[i], arr2[j]);
}
 
int main()
{
    int arr1[] = { 1, 2, 3 }; // first set
    int arr2[] = { 4, 5, 6 }; // second set
    int n1 = sizeof(arr1) / sizeof(arr1[0]);
    int n2 = sizeof(arr2) / sizeof(arr2[0]);
    findCart(arr1, arr2, n1, n2);
    return 0;
}

// Java Program to find the
// Cartesian Product of Two Sets
import java.io.*;
import java.util.*;
 
class GFG {
 
    static void findCart(int arr1[], int arr2[],
                                    int n, int n1)
    {
        for (int i = 0; i < n; i++)
          for (int j = 0; j < n1; j++)
            System.out.print("{"+ arr1[i]+", "
                             + arr2[j]+"}, ");
    }
    // Driver code
    public static void main (String[] args) {
         
        // first set
        int arr1[] = { 1, 2, 3 };
         
        // second set
        int arr2[] = { 4, 5, 6 };
         
        int n1 = arr1.length;
        int n2 = arr2.length;
        findCart(arr1, arr2, n1, n2);
    }
}
 
 
// This code is contributed by Nikita Tiwari.

# Python3 Program to find the
# Cartesian Product of Two Sets
 
def findCart(arr1, arr2, n, n1):
 
    for i in range(0,n):
        for j in range(0,n1):
            print("{",arr1[i],", ",arr2[j],"}, ",sep="",end="")
 
# Driver code
arr1 = [ 1, 2, 3 ] # first set
arr2 = [ 4, 5, 6 ] # second set
 
n1 = len(arr1) # sizeof(arr1[0])
n2 = len(arr2) # sizeof(arr2[0]);
 
findCart(arr1, arr2, n1, n2);
 
# This code is contributed
# by Smitha Dinesh Semwal

// C# Program to find the
// Cartesian Product of Two Sets
using System;
 
class GFG {
 
    static void findCart(int []arr1, int []arr2,
                                    int n, int n1)
    {
        for (int i = 0; i < n; i++)
            for (int j = 0; j < n1; j++)
                Console.Write("{" + arr1[i] + ", "
                                + arr2[j] + "}, ");
    }
     
    // Driver code
    public static void Main () {
         
        // first set
        int []arr1 = { 1, 2, 3 };
         
        // second set
        int []arr2 = { 4, 5, 6 };
         
        int n1 = arr1.Length;
        int n2 = arr2.Length;
         
        findCart(arr1, arr2, n1, n2);
    }
}
 
 
// This code is contributed by vt_m.

<?php
// PHP Program to find the
// Cartesian Product of Two Sets
 
function findCart($arr1, $arr2, $n, $n1)
{
    for ($i = 0; $i < $n; $i++)
        for ( $j = 0; $j < $n1; $j++)
            echo "{", $arr1[$i] ," , ",
                      $arr2[$j], "}",",";
}
 
// Driver Code
 
// first set
$arr1 = array ( 1, 2, 3 );
 
// second set
$arr2 = array ( 4, 5, 6 );
$n1 = sizeof($arr1) ;
$n2 = sizeof($arr2);
findCart($arr1, $arr2, $n1, $n2);
 
// This code is contributed by m_kit.
?>

<script>
 
// JavaScript Program to find the
// Cartesian Product of Two Set
 
    function findCart(arr1, arr2, n, n1)
    {
        for (let i = 0; i < n; i++)
          for (let j = 0; j < n1; j++)
            document.write("{"+ arr1[i]+", "
                             + arr2[j]+"}, ");
    }
   
// Driver Code
 
        // first set
        let arr1 = [ 1, 2, 3 ];
           
        // second set
        let arr2 = [4, 5, 6 ];
           
        let n1 = arr1.length;
        let n2 = arr2.length;
        findCart(arr1, arr2, n1, n2);
        
       // This code is contributed by chinmoy1997pal.
</script>

Producción : 
 

{{1, 4}, {1, 5}, {1, 6}, {2, 4}, {2, 5}, {2, 6}, {3, 4}, {3, 5}, {3, 6}}

Ejemplos prácticos: 
1) Un juego de cartas es el producto cartesiano de un juego de cuatro elementos a un juego de 13 elementos.
2) Un sistema de coordenadas bidimensional es un producto cartesiano de dos conjuntos de números reales.
Referencia:  
https://en.wikipedia.org/wiki/Cartesian_product