1 files changed, 35 insertions, 0 deletions
diff --git a/hardinfo2/nqueens.c b/hardinfo2/nqueens.c
new file mode 100644
index 00000000..9d36a82e
--- /dev/null
+++ b/hardinfo2/nqueens.c
@@ -0,0 +1,35 @@
+/*
+ * N-Queens Problem Solver
+ * Found somewhere on the Internet; can't remember where. Possibly Wikipedia.
+ */
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+#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;
+}