// Ambrose Sterr
// 04/05/06
// Version 3.0.1
// Doesn't compile.

#include <stdio.h>
#include <stdlib.h>

void backTrack(int, int*);
void recurse(int, int*, int*, int*, int*, int);
int test (int*, int*);
void pSums(int, int*, int*);

int main(void)
{
    int n = 11;                     // Some default variables
    int size = 2;
    int r[2] = {4, 5};
    int s[2];
    pSums(size, r, s);              // To calculate a list of partial sums
    if (s[1] == 9)                  // Just a test
    {
        printf("ok.\n");
    }
    backTrack(n, s);                // Gets the program going
    return 0;
}
void backTrack(int n, int s[])
{
    int used[9];                    // Setup and intialization of the arrays to keep track of the numbers used and their differences.
    int h[11];                      // The difference array.
    int i;                          // The iteration of first numbers.
    for (i = 1; i < 10; i++)
    {
        int j;
        int count = 1;
        for (j = 0; j < 9; j++)
        {
            used[j] = 0;
        }
        for (j = 0; j < n; j++)
        {
            h[j] = 0;
        }
        used[i]++;                  // The first number is used.
        int list[11];               // This is where the program blows apart, with "Missing '}'"
        list[0] = i;
        recurse(n, s, used, h, list, count);    // This starts recursive scanning of the rest of the list.
    }
}
void recurse(int n, int s[], int used[], int h[], int list[], int count)
{
    if (count != n)                 // If the list isn't filled in...
    {
        int i;
        for (i = 1; i <= n; i++)    // Look for the next number to add...
        {
            if ((used[i] == 0)&&(h[abs(list[count-1]-i)]==0))   // ...make sure it's a good one...
            {
                list[count] = i;
                used[i]++;
                h[abs(list[count-1]-i)]++;
                recurse(n, s, used, h, list, count+1);          // ...then head deeper in.
                h[abs(list[count-1]-i)]--;
                used[i]--;
            }
        }
    }
    else                            // But if it is...
    {
        if (test(list, s) == 1)     // Check the list
        {
            printf("We got one!\n");        // Report a find!
        }
    }
	return 0;
}
int test (int list[], int s[])      // Checks for the extra property
{
    if (abs(list[s[0]]-list[0])==abs(list[s[0]+1]-list[s[0]]))
    {
        if (abs(list[s[1]]-list[s[0]+1])==abs(list[s[1]+1]-list[s[1]]))
        {
            return 1;               // Returns 1 if it is what I'm looking for
        }
    }
    return 0;                       // And 0 if it's not.
}
void pSums(int size, int r[], int s[])      // Makes a partial sum list out of the passed list.
{
    int i;
    s[0] = r[0];
    for (i = 1; i < size; i++)
    {
        s[i] = s[i-1] + r[i];
    };
}