8 queen puzzle solver

8queen.c

#include <stdio.h>

/*
  You can define the size of Queens
*/
#define QUEEN 8

int row[QUEEN+1];
int l[2*QUEEN];
int r[2*QUEEN];
int rt[QUEEN+1];
int c=0;
void solve8queen(int level)
{
  if (level <= QUEEN)
  {
    int i = 1;
    while(i<=QUEEN)
    {
        if(row[i]!=1&&l[level+i-1]!=1&&r[QUEEN+i-level]!=1)
        {
          row[i] = l[level+i-1] = r[QUEEN+i-level] = 1;
          rt[level] = i;
          solve8queen(level+1);
          row[i] = l[level+i-1] = r[QUEEN+i-level] = 0;
        }
        i++;
    }
  }
  else
  {
    c++;
    int i;
    for(i = 1; i<=QUEEN; i++)
    {
      printf("\t%d", rt[i]);
    }
    printf("\n");
  }
}

int
main(int ac, char *av[])
{
  solve8queen(1);
  printf("totally: %d solutions\n", c);
  return 0;
}

This is for n queen:

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

void solve8queen(int level, int n,int *row, int *l, int *r, int *c)
{
    if (level <= n)
    {
        int i = 1;
        while(i<=n)
        {
            if(row[i]!=1&&l[level+i-1]!=1&&r[n+i-level]!=1)
            {
                row[i] = l[level+i-1] = r[n+i-level] = 1;
                solve8queen(level+1, n,row,l,r,c);
                row[i] = l[level+i-1] = r[n+i-level] = 0;
            }
            i++;
        }
    }
    else
    {
        (*c)++;
    }
}
int totalNQueens(int n) {
    int row[n+1];
    int l[2*n];
    int r[2*n];
    int c=0;
    solve8queen(1,n,row,l,r,&c);
    return c;
}

int
main(int ac, char *av[])
{
  printf("totally: %d solutions\n", totalNQueens(atoi(av[1])));
  return 0;
}

Actually, we can use bit to represent the row, l, r, rt, but it is not straightforward. Bit operations are always cool techs.