nine-five-four_zero.c

/*

    nine-five-four_zero.c

    Task from Graham Holmes:
    https://www.facebook.com/groups/242739573272753/permalink/874176896795681/

    NINE - FIVE - FOUR = ZERO

    Replace each letter with a digit from 0 to 9 to make this sum add up.
    No two letters can have the same digit,
    and no two digits can share the same letter.
    Leading zeroes aren't permitted.
    What is the value of ZERO?

 Result:
 Value of ZERO is 1564.

 There are 4 solutions:

 NINE - FIVE - FOUR = ZERO
 8085 - 3025 - 3496 = 1564

 NINE - FIVE - FOUR = ZERO
 8085 - 3095 - 3426 = 1564

 NINE - FIVE - FOUR = ZERO
 8785 - 3725 - 3496 = 1564

 NINE - FIVE - FOUR = ZERO
 8785 - 3795 - 3426 = 1564


    You can find all my C programs at Dragan Milicev's pastebin:

    https://pastebin.com/u/dmilicev

*/

#include <stdio.h>

// Returns 1 if all digits are different from each other, otherwise returns 0.
int allDifferent(int n, int i, int e, int f, int v, int o, int u, int r, int z)
{
    int arr[9]={n,i,e,f,v,o,u,r,z};
    int len = sizeof(arr) / sizeof(arr[0]);
    int x, y;

    for(x=0; x<len; x++)
      for(y=x+1; y<len; y++)
        if( arr[x] == arr[y] )
            return 0;

    return 1;
}

int main(void)
{
    int n, i, e, f, v, o, u, r, z, nine, five, four, zero, solved=0, number_of_solutions=0;

    for(n=1; n<10; n++)
      for(i=0; i<10; i++)
        for(e=0; e<10; e++)
          for(f=1; f<10; f++)
            for(v=0; v<10; v++)
              for(o=0; o<10; o++)
                for(u=0; u<10; u++)
                  for(r=0; r<10; r++)
                    for(z=1; z<10; z++)
                    {
                      nine = n*1000 + i*100 + n*10 + e;
                      five = f*1000 + i*100 + v*10 + e;
                      four = f*1000 + o*100 + u*10 + r;
                      zero = z*1000 + e*100 + r*10 + o;

                      if( nine - five - four == zero  &&
                          allDifferent(n,i,e,f,v,o,u,r,z) )
                      {
                        solved = 1;
                        number_of_solutions++;
                        printf("\n NINE - FIVE - FOUR = ZERO \n");
                        printf("\n %d%d%d%d - %d%d%d%d - %d%d%d%d = %d%d%d%d \n\n",
                                n,i,n,e, f,i,v,e, f,o,u,r, z,e,r,o );
                      }
                    }

    if( !solved )
        printf("\n There is no solution. \n");
    else
        printf("\n There are %d solutions. \n", number_of_solutions);


    return 0;

} // main()