From 056a88ee9c2c9e26f9712d14c645e367d851f394 Mon Sep 17 00:00:00 2001
From: Charles <sircharlesaze@gmail.com>
Date: Tue, 6 Aug 2019 16:56:43 +0200
Subject: c05

- primality test correction for ft_is_prime and ft_find_next_prime
- queens puzzle solved with backtracking (similar to rush01)
---
 c05/ex08/ft_queens.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 c05/ex08/ft_queens.c

(limited to 'c05/ex08')

diff --git a/c05/ex08/ft_queens.c b/c05/ex08/ft_queens.c
new file mode 100644
index 0000000..ba2c742
--- /dev/null
+++ b/c05/ex08/ft_queens.c
@@ -0,0 +1,62 @@
+#include <unistd.h>
+#define TRUE 1
+#define FALSE 0
+#define BOARD_SIZE 10
+#define ABS(x) (x < 0 ? -(x) : x)
+
+void    ft_putchar(char c)
+{
+    write(1, &c, 1);
+}
+
+static void print_cols(int cols[BOARD_SIZE])
+{
+    int i;
+
+    i = 0;
+    while (i < BOARD_SIZE)
+        ft_putchar(cols[i++] + '0'); // maybe +1
+    ft_putchar('\n');
+}
+
+static int  valid_position(int cols[BOARD_SIZE], int x, int y)
+{
+    int i;
+
+    i = 0;
+    while (i < x)
+    {
+        if (y == cols[i])
+            return (FALSE);
+        if (ABS(x - i) == ABS(y - cols[i]))
+            return (FALSE);
+        i++;
+    }
+    return (TRUE);
+}
+
+static  void    solve(int cols[BOARD_SIZE], int x)
+{
+    int i;
+
+    if (x == BOARD_SIZE)
+    {
+        print_cols(cols);
+        return ;
+    }
+    i = -1;
+    while (++i < BOARD_SIZE)
+    {
+        if (!valid_position(cols, x, i))
+            continue ;
+        cols[x] = i;
+        solve(cols, x + 1);
+    }
+}
+
+void    ft_queens(void) // may have bad name
+{
+    int cols[BOARD_SIZE];
+
+    solve(cols, 0);
+}
-- 
cgit