From: Mart Lubbers <mart@martlubbers.net>
Date: Mon, 20 Dec 2021 10:38:14 +0000 (+0100)
Subject: day 18
X-Git-Url: https://git.martlubbers.net/?a=commitdiff_plain;h=3f719e53a93064f75711d41ac38d0ae163354cf7;p=advent21.git

day 18
---

diff --git a/18a.c b/18a.c
index 719c3f0..acec8d3 100644
--- a/18a.c
+++ b/18a.c
@@ -4,52 +4,149 @@
 #include <ctype.h>
 
 struct number {
-	int depth;
 	int number;
+	int depth;
+	struct number *prev;
+	struct number *next;
 };
 
-int parse_number(struct number numbers[])
+void print_number(struct number *head)
+{
+	for (struct number *e = head; e != NULL; e = e->next)
+		printf("(%d,%d) ", e->number, e->depth);
+	printf("\n");
+}
+
+struct number *parse_comp(struct number *prev, int *depth)
 {
-	int ns = 0;
-	int depth = 0;
 	int c = getchar();
-	while ((c = getchar()) != '\n') {
-		switch(c) {
-		case '[':
-			depth++;
-			break;
-		case ']':
-			depth--;
-			break;
-		case ',':
-			break;
-		default:
-			if (isdigit(c))
-				numbers[ns++] = (struct number){.depth=depth, .number=c-'0'};
-			else
-				printf("halp\n");
-			break;
-		}
+	if (isdigit(c)) {
+		struct number *r = malloc(sizeof(struct number));
+		r->next = NULL;
+		r->prev = prev;
+		if (prev != NULL)
+			prev->next = r;
+		r->number = c-'0';
+		r->depth = *depth;
+		return r;
+	} else if (c == ',') {
+		return parse_comp(prev, depth);
+	} else if (c == '[') {
+		*depth = *depth+1;
+		return parse_comp(prev, depth);
+	} else if (c == ']') {
+		*depth = *depth-1;
+		return parse_comp(prev, depth);
+	} else if (c != '\n' && c != EOF) {
+		printf("unknown character: '%c': %d\n", c, c);
 	}
-	return ns;
+	return NULL;
 }
 
-void print_number(struct number n[], int ns)
+struct number *parse_number()
 {
-	int olddepth = 0;
-	for (int i = 0; i<ns; i++) {
-		if (n[i].depth > olddepth)
-			printf("[");
-		else if (n[i].depth < olddepth)
-			printf("]");
-		printf("%d ", n[i].number);
-		olddepth = n[i].depth;
+	int depth = 0;
+	struct number *head = parse_comp(NULL, &depth);
+	if (head == NULL)
+		return NULL;
+	struct number *e = head;
+	while ((e = parse_comp(e, &depth)) != NULL)
+		;
+	return head;
+}
+
+void add_number(struct number *sum, struct number *oper)
+{
+	//increase depth of sum
+	struct number *e = sum;
+	for (; e->next != NULL; e = e->next)
+		e->depth++;
+	//append
+	e->next = oper;
+	oper->prev = e;
+	//increase depth of oper
+	for (; e != NULL; e = e->next)
+		e->depth++;
+}
+
+bool explode_number(struct number *e)
+{
+	if (e->depth <= 4)
+		return false;
+	struct number *l = e;
+	struct number *r = e->next;
+	if (l->prev != NULL)
+		l->prev->number += l->number;
+	if (r->next != NULL)
+		r->next->number += r->number;
+	l->number = 0;
+	l->depth--;
+	l->next = r->next;
+	if (l->next != NULL)
+		l->next->prev = l;
+	if (l->prev != NULL)
+		e = l->prev;
+	free(r);
+	return true;
+}
+
+bool split_number(struct number *e)
+{
+	if (e->number < 10)
+		return false;
+	struct number *i = malloc(sizeof(struct number));
+	i->number = e->number/2 + (e->number%2);
+	i->depth = e->depth+1;
+	i->prev = e;
+	i->next = e->next;
+	e->next = i;
+	e->number = e->number/2;
+	e->depth = e->depth+1;
+	return true;
+}
+
+void reduce_number(struct number *n)
+{
+	bool appliedaction;
+	do {
+		appliedaction = false;
+		for (struct number *e = n; e != NULL && !appliedaction; e = e->next)
+			appliedaction |= explode_number(e);
+		for (struct number *e = n; e != NULL && !appliedaction; e = e->next)
+			appliedaction |= split_number(e);
+	} while (appliedaction);
+}
+
+int magnitude_number(struct number *n)
+{
+	int maxdepth = 4;
+	while (n->next != NULL) {
+		for (struct number *e = n; e != NULL; e = e->next) {
+			if (e->depth == maxdepth) {
+				struct number *l = e;
+				struct number *r = e->next;
+				l->depth--;
+				l->number = l->number*3 + r->number*2;
+				l->next = r->next;
+				if (r->next != NULL)
+					r->next->prev = l;
+				free(r);
+			}
+		}
+		maxdepth--;
 	}
+	int r = n->number;
+	free(n);
+	return r;
 }
 
 int main ()
 {
-	struct number n[100];
-	int ns = parse_number(n);
-	print_number(n, ns);
+	struct number *sum = parse_number();
+	struct number *oper;
+	while ((oper = parse_number()) != NULL) {
+		add_number(sum, oper);
+		reduce_number(sum);
+	}
+	printf("%d\n", magnitude_number(sum));
 }
diff --git a/18b.c b/18b.c
new file mode 100644
index 0000000..490b038
--- /dev/null
+++ b/18b.c
@@ -0,0 +1,185 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <ctype.h>
+
+struct number {
+	int number;
+	int depth;
+	struct number *prev;
+	struct number *next;
+};
+
+void print_number(struct number *head)
+{
+	for (struct number *e = head; e != NULL; e = e->next)
+		printf("(%d,%d) ", e->number, e->depth);
+	printf("\n");
+}
+
+struct number *parse_comp(struct number *prev, int *depth)
+{
+	int c = getchar();
+	if (isdigit(c)) {
+		struct number *r = malloc(sizeof(struct number));
+		r->next = NULL;
+		r->prev = prev;
+		if (prev != NULL)
+			prev->next = r;
+		r->number = c-'0';
+		r->depth = *depth;
+		return r;
+	} else if (c == ',') {
+		return parse_comp(prev, depth);
+	} else if (c == '[') {
+		*depth = *depth+1;
+		return parse_comp(prev, depth);
+	} else if (c == ']') {
+		*depth = *depth-1;
+		return parse_comp(prev, depth);
+	} else if (c != '\n' && c != EOF) {
+		printf("unknown character: '%c': %d\n", c, c);
+	}
+	return NULL;
+}
+
+struct number *parse_number()
+{
+	int depth = 0;
+	struct number *head = parse_comp(NULL, &depth);
+	if (head == NULL)
+		return NULL;
+	struct number *e = head;
+	while ((e = parse_comp(e, &depth)) != NULL)
+		;
+	return head;
+}
+
+void add_number(struct number *sum, struct number *oper)
+{
+	//increase depth of sum
+	struct number *e = sum;
+	for (; e->next != NULL; e = e->next)
+		e->depth++;
+	//append
+	e->next = oper;
+	oper->prev = e;
+	//increase depth of oper
+	for (; e != NULL; e = e->next)
+		e->depth++;
+}
+
+bool explode_number(struct number *e)
+{
+	if (e->depth <= 4)
+		return false;
+	struct number *l = e;
+	struct number *r = e->next;
+	if (l->prev != NULL)
+		l->prev->number += l->number;
+	if (r->next != NULL)
+		r->next->number += r->number;
+	l->number = 0;
+	l->depth--;
+	l->next = r->next;
+	if (l->next != NULL)
+		l->next->prev = l;
+	if (l->prev != NULL)
+		e = l->prev;
+	free(r);
+	return true;
+}
+
+bool split_number(struct number *e)
+{
+	if (e->number < 10)
+		return false;
+	struct number *i = malloc(sizeof(struct number));
+	i->number = e->number/2 + (e->number%2);
+	i->depth = e->depth+1;
+	i->prev = e;
+	i->next = e->next;
+	e->next = i;
+	e->number = e->number/2;
+	e->depth = e->depth+1;
+	return true;
+}
+
+void reduce_number(struct number *n)
+{
+	bool appliedaction;
+	do {
+		appliedaction = false;
+		for (struct number *e = n; e != NULL && !appliedaction; e = e->next)
+			appliedaction |= explode_number(e);
+		for (struct number *e = n; e != NULL && !appliedaction; e = e->next)
+			appliedaction |= split_number(e);
+	} while (appliedaction);
+}
+
+int magnitude_number(struct number *n)
+{
+	int maxdepth = 4;
+	while (n->next != NULL) {
+		for (struct number *e = n; e != NULL; e = e->next) {
+			if (e->depth == maxdepth) {
+				struct number *l = e;
+				struct number *r = e->next;
+				l->depth--;
+				l->number = l->number*3 + r->number*2;
+				l->next = r->next;
+				if (r->next != NULL)
+					r->next->prev = l;
+				free(r);
+			}
+		}
+		maxdepth--;
+	}
+	int r = n->number;
+	free(n);
+	return r;
+}
+
+struct number *copy_number(struct number *n)
+{
+	struct number *copy = malloc(sizeof(struct number));
+	copy->number = n->number;
+	copy->depth = n->depth;
+	copy->prev = NULL;
+	copy->next = NULL;
+	struct number *prev = copy;
+	for (struct number *e = n->next; e != NULL; e = e->next) {
+		struct number *c = malloc(sizeof(struct number));
+		c->depth = e->depth;
+		c->number = e->number;
+		c->next = NULL;
+		c->prev = prev;
+		if (prev != NULL)
+			prev->next = c;
+		prev = c;
+	}
+	return copy;
+}
+
+int main ()
+{
+	int nnumber = 0;
+	struct number *numbers[100] = {0};
+	while ((numbers[nnumber] = parse_number()) != NULL)
+		nnumber++;
+
+	int maxmagnitude = 0;
+	for (int i = 0; i<nnumber; i++) {
+		for (int j = 0; j<nnumber; j++) {
+			if (i == j)
+				continue;
+			struct number *e = copy_number(numbers[i]);
+			add_number(e, copy_number(numbers[j]));
+			reduce_number(e);
+			int magnitude = magnitude_number(e);
+			if (magnitude > maxmagnitude)
+				maxmagnitude = magnitude;
+		}
+	}
+	printf("%d\n", maxmagnitude);
+}
diff --git a/18e.txt b/18e.txt
new file mode 100644
index 0000000..61b0df6
--- /dev/null
+++ b/18e.txt
@@ -0,0 +1,2 @@
+[[[[4,3],4],4],[7,[[8,4],9]]]
+[1,1]
diff --git a/18e2.txt b/18e2.txt
new file mode 100644
index 0000000..f430960
--- /dev/null
+++ b/18e2.txt
@@ -0,0 +1,2 @@
+[[[[[9,8],1],2],3],4]
+
diff --git a/18e3.txt b/18e3.txt
new file mode 100644
index 0000000..41c8d15
--- /dev/null
+++ b/18e3.txt
@@ -0,0 +1 @@
+[7,[6,[5,[4,[3,2]]]]]
diff --git a/18e4.txt b/18e4.txt
new file mode 100644
index 0000000..9f59172
--- /dev/null
+++ b/18e4.txt
@@ -0,0 +1 @@
+[[6,[5,[4,[3,2]]]],1]
diff --git a/18e5.txt b/18e5.txt
new file mode 100644
index 0000000..f212f83
--- /dev/null
+++ b/18e5.txt
@@ -0,0 +1,4 @@
+[1,1]
+[2,2]
+[3,3]
+[4,4]
diff --git a/18e6.txt b/18e6.txt
new file mode 100644
index 0000000..d1c17ef
--- /dev/null
+++ b/18e6.txt
@@ -0,0 +1 @@
+[[[[3,0],[5,3]],[4,4]],[5,5]]
diff --git a/18e7.txt b/18e7.txt
new file mode 100644
index 0000000..85acce5
--- /dev/null
+++ b/18e7.txt
@@ -0,0 +1,6 @@
+[1,1]
+[2,2]
+[3,3]
+[4,4]
+[5,5]
+[6,6]
diff --git a/18e8.txt b/18e8.txt
new file mode 100644
index 0000000..70e9071
--- /dev/null
+++ b/18e8.txt
@@ -0,0 +1,10 @@
+[[[0,[4,5]],[0,0]],[[[4,5],[2,6]],[9,5]]]
+[7,[[[3,7],[4,3]],[[6,3],[8,8]]]]
+[[2,[[0,8],[3,4]]],[[[6,7],1],[7,[1,6]]]]
+[[[[2,4],7],[6,[0,5]]],[[[6,8],[2,8]],[[2,1],[4,5]]]]
+[7,[5,[[3,8],[1,4]]]]
+[[2,[2,2]],[8,[8,1]]]
+[2,9]
+[1,[[[9,3],9],[[9,0],[0,7]]]]
+[[[5,[7,4]],7],1]
+[[[[4,2],2],6],[8,7]]
diff --git a/Makefile b/Makefile
index a350a35..b6f6074 100644
--- a/Makefile
+++ b/Makefile
@@ -1,9 +1,9 @@
 CFLAGS:=-Wall -Wextra -O3
 LFLAGS:=-f
 
-BINARIES:=$(filter-out 18a 18b 19a 19b,$(foreach num,$(shell seq -f '%02.0f' 1 20),$(num)a $(num)b))
+BINARIES:=$(filter-out 19a 19b,$(foreach num,$(shell seq -f '%02.0f' 1 20),$(num)a $(num)b))
 
-all: 
+all: $(BINARIES)
 
 clean:
 	$(RM) *.o a.out $(BINARIES)