Kevin, really good brute force solver, you've made! Are you sure return solve(a, b, c+1, 0) if d==3 return solve(a, b+1, 0, d) if c==3 return solve(a+1, 0, c, d) if b==3 shouldn't be return solve(a, b, c+1, 0) if d==3 return solve(a, b+1, 0, 0) if c==3 return solve(a+1, 0, 0, 0) if b==3 ? (I rewrote it in Ruby) regards Christer 2005-12-29 21:06:45.618 2005-12-29 21:06:45.551