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/ex06/ft_is_prime.c        | 14 ++++------
 c05/ex07/ft_find_next_prime.c | 19 ++++++-------
 c05/ex08/ft_queens.c          | 62 +++++++++++++++++++++++++++++++++++++++++++
 c05/main.c                    | 12 ++++++---
 4 files changed, 83 insertions(+), 24 deletions(-)
 create mode 100644 c05/ex08/ft_queens.c

diff --git a/c05/ex06/ft_is_prime.c b/c05/ex06/ft_is_prime.c
index 3c83061..658fefb 100644
--- a/c05/ex06/ft_is_prime.c
+++ b/c05/ex06/ft_is_prime.c
@@ -13,7 +13,6 @@
 int	ft_is_prime(int nb)
 {
 	long unsigned int	i;
-	long unsigned int	nbu;
 
 	if (nb <= 1)
 		return (0);
@@ -21,15 +20,12 @@ int	ft_is_prime(int nb)
 		return (1);
 	if (nb % 2 == 0 || nb % 3 == 0)
 		return (0);
-	i = 1;
-	nbu = nb;
-	while (i * i <= nbu) // ne fonctionne pas de 7 a 41
+	i = 5;
+	while (i * i <= nb)
 	{
-		if (nbu % (i * 6 - 1) == 0)
-			return (0);
-		if (nbu % (i * 6 + 1) == 0)
-			return (0);
-		i += 1;
+        if (nb % i == 0 || nb % (i + 2) == 0)
+            return (0);
+        i += 6;
 	}
 	return (1);
 }
diff --git a/c05/ex07/ft_find_next_prime.c b/c05/ex07/ft_find_next_prime.c
index 80227da..d8650eb 100644
--- a/c05/ex07/ft_find_next_prime.c
+++ b/c05/ex07/ft_find_next_prime.c
@@ -10,10 +10,10 @@
 /*                                                                            */
 /* ************************************************************************** */
 
-int	is_prime(int nb)
+
+static int	is_prime(int nb)
 {
 	long unsigned int	i;
-	long unsigned int	nbu;
 
 	if (nb <= 1)
 		return (0);
@@ -21,20 +21,17 @@ int	is_prime(int nb)
 		return (1);
 	if (nb % 2 == 0 || nb % 3 == 0)
 		return (0);
-	i = 1;
-	nbu = nb;
-	while (i * i <= nbu)
+	i = 5;
+	while (i * i <= nb)
 	{
-		if (nbu % (i * 6 - 1) == 0)
-			return (0);
-		if (nbu % (i * 6 + 1) == 0)
-			return (0);
-		i += 1;
+        if (nb % i == 0 || nb % (i + 2) == 0)
+            return (0);
+        i += 6;
 	}
 	return (1);
 }
 
-int	ft_find_next_prime(int nb)
+int     ft_find_next_prime(int nb)
 {
 	while (!is_prime(nb))
 		nb++;
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);
+}
diff --git a/c05/main.c b/c05/main.c
index bdb7ad7..f66caf9 100644
--- a/c05/main.c
+++ b/c05/main.c
@@ -9,6 +9,7 @@
 #include "ex05/ft_sqrt.c"
 #include "ex06/ft_is_prime.c"
 #include "ex07/ft_find_next_prime.c"
+#include "ex08/ft_queens.c"
 
 int main()
 {
@@ -81,10 +82,10 @@ int main()
 	printf("prime(%d) = %d\n", 899, ft_is_prime(899));
 	printf("prime(%d) = %d\n", 289, ft_is_prime(289));
 	printf("prime(%d) = %d\n", 2147483424, ft_is_prime(2147483424));
-	/*for (int i = INT_MAX; i > INT_MAX - 1000000; i--)*/
-		/*printf("%d is %d\n", i, ft_is_prime(i));*/
-	for (int i = 3; i <= 41; i++)
-		printf("%d is %d\n", i, ft_is_prime(i));
+	// for (int i = INT_MAX; i > INT_MAX - 1000000; i--)
+		// printf("%d is %d\n", i, ft_is_prime(i));
+	// for (int i = 3; i <= 41; i++)
+		// printf("%d is %d\n", i, ft_is_prime(i));
 
 	printf("---------------------\n");
 	printf("nextp(%d) = %d\n", 21, ft_find_next_prime(21));
@@ -93,4 +94,7 @@ int main()
 	printf("nextp(%d) = %d\n", 2147483600, ft_find_next_prime(2147483600));
 	/*for (int i = INT_MAX; i > INT_MAX - 1000000; i--)*/
 		/*printf("%d is %d\n", i, ft_find_next_prime(i));*/
+
+	printf("---------------------\n");
+    // ft_queens();
 }
-- 
cgit