From 4979bb6cbbbe39eb44c32530cd13f86bf44e5d77 Mon Sep 17 00:00:00 2001 From: Simon Quigley Date: Mon, 19 Jun 2017 14:38:48 -0500 Subject: Import Upstream version 0.5c --- nqueens.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 nqueens.c (limited to 'nqueens.c') diff --git a/nqueens.c b/nqueens.c new file mode 100644 index 00000000..838731c4 --- /dev/null +++ b/nqueens.c @@ -0,0 +1,37 @@ +/* + * N-Queens Problem Solver + * Found somewhere on the Internet; can't remember where. Possibly Wikipedia. + */ +#include +#include +#include + +#define QUEENS 11 + +int row[QUEENS]; + +bool safe(int x, int y) +{ + int i; + for (i = 1; i <= y; i++) + if (row[y - i] == x || row[y - i] == x - i || row[y - i] == x + i) + return false; + return true; +} + +int nqueens(int y) +{ + int x; + + for (x = 0; x < QUEENS; x++) { + if (safe((row[y - 1] = x), y - 1)) { + if (y < QUEENS) { + nqueens(y + 1); + } else { + break; + } + } + } + + return 0; +} -- cgit v1.2.3