MH

/*
ID: teh_min1
PROG: checker
LANG: C
Checker Challenge
Done by Teh Ming Han
*/

/*
Algorithm: Recursion

Notes:
If n is even, we can compute half a board and then flip along the x axis to generate the other half of the board.
this means we only need to generate half the board if n is even.

If n is odd, we compute half a board and then (half + 1 rows) of the board.
Then we sum then up to get the answer.

*/

#include <stdio.h>
#include <string.h>

//#include <iostream.h>

int ans[3][14] = {0}, ans_c = 0;

int board[14] = {0}, n, size;

int recur(int r){
    if (r==size){ //jackpot
        if (ans_c<3) memcpy(ans[ans_c],board,sizeof(int)*size);
        ans_c++;
        return 0;
    }

    int a;
    char cans[28] = {'#'};

    for (a=1;a<r;a++){
        cans[board[a]] = '@';
        cans[board[a]-(r-a)] = '@';
        cans[board[a]+(r-a)] = '@';
    }

    for (a=1;a<=n;a++) //start checking if position is suitable
        if (cans[a]!='@'){
            board[r] = a;
            recur(r+1);
        }

    return 0;
}

int main(){

    int i,a;

    FILE * in = fopen("checker.in","r");
    fscanf(in,"%d",&n);
    fclose(in);

    size = n + 1;

    int ans_temp,limit;

    if (n==6) limit = n;
    else limit = (n+1)/2;

    for (i=1;i<=limit;i++){
        ans_temp = ans_c;

        board[1] = i;
        recur(2);
    }

    if (n%2==0 && n>6) ans_c *= 2;
    else if (n%2==1 && n>6) ans_c = ans_c + ans_temp;

    FILE *out = fopen ("checker.out", "w");

    for (i=0;i<3;i++){
        for (a=1;a<n;a++)
            fprintf(out,"%d ",ans[i][a]);
        fprintf(out,"%d\n",ans[i][n]); //solve the spacing prob
    }
    fprintf(out,"%d\n",ans_c);
    printf("%d\n",ans_c);
    fclose(out);

    return 0;
}