From d2969bd72436e81a1c2d4c0ecb5d66cb6654fc89 Mon Sep 17 00:00:00 2001
From: Vincent Douillet <vincent@vdouillet.fr>
Date: Wed, 7 Dec 2022 12:56:20 +0100
Subject: day 5 part 2

---
 05.c | 48 +++++++++++++++++++++++++++++-------------------
 1 file changed, 29 insertions(+), 19 deletions(-)

diff --git a/05.c b/05.c
index b127da7..4122c46 100644
--- a/05.c
+++ b/05.c
@@ -1,6 +1,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <stdbool.h>
 #include "queue.h"
 #include "input.h"
 
@@ -8,16 +9,25 @@
 #define EXPECTED1 70369L
 #define EXPECTED2 203002L
 #define STACK_COUNT 9
+	
+SLIST_HEAD(crate_list, crate) head[STACK_COUNT];
+struct crate {
+	char crate_char;
+	SLIST_ENTRY(crate) entries;
+};
+struct crate* last_crate[STACK_COUNT];
 
-void part1(struct input_str* input) {
-	// parse stacks
-	SLIST_HEAD(crate_list, crate) head[STACK_COUNT];
-	struct crate {
-		char crate_char;
-		SLIST_ENTRY(crate) entries;
-	};
-	struct crate* last_crate[STACK_COUNT];
+void move_9001(int count, struct crate_list* from_head, struct crate* from_crate, struct crate_list* to_head) {
+	// use a recursion to move the crates from bottom up
+	if(count > 1) {
+		move_9001(count - 1, from_head, SLIST_NEXT(from_crate, entries), to_head);
+	}
+	SLIST_REMOVE(from_head, from_crate, crate, entries);
+	SLIST_INSERT_HEAD(to_head, from_crate, entries);
+}
 
+void move_crates(struct input_str* input, bool is_crane_9000) {
+	// parse stacks
 	for(int i = 0; i < STACK_COUNT; i++) {
 		SLIST_INIT(head + i);
 		last_crate[i] = SLIST_FIRST(head + i);
@@ -63,14 +73,17 @@ void part1(struct input_str* input) {
 		//printf("move %d from %d to %d\n", crate_count, from, to);
 		from--;
 		to--;
-		for(int m = 0; m < crate_count; m++) {
-			struct crate* cc = SLIST_FIRST(head + from);
-			SLIST_REMOVE_HEAD(head + from, entries);
-			SLIST_INSERT_HEAD(head + to, cc, entries);
-		}
+		if(is_crane_9000)
+			for(int m = 0; m < crate_count; m++) {
+				struct crate* cc = SLIST_FIRST(head + from);
+				SLIST_REMOVE_HEAD(head + from, entries);
+				SLIST_INSERT_HEAD(head + to, cc, entries);
+			}
+		else
+			move_9001(crate_count, head + from, SLIST_FIRST(head + from), head + to);
 	}
 
-	// print result, expected is BSDMQFLSP with my input
+	// print result
 	for(int s = 0; s < STACK_COUNT; s++) {
 		struct crate* cc = SLIST_FIRST(head + s);
 		printf("%c", cc->crate_char);
@@ -80,17 +93,14 @@ void part1(struct input_str* input) {
 	// TODO free all the crates
 }
 
-void part2(struct input_str* input) {
-}
-
 int main() {
 	// read input
 	struct input_str input;
 	input_str_read(&input, INPUT);
 
 	// do stuff
-	part1(&input);
-	part2(&input);
+	move_crates(&input, true); // BSDMQFLSP expected
+	move_crates(&input, false); // PGSQBFLDP expected
 
 	// cleanup & exit
 	input_str_free(&input);
-- 
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