From 1f75d7c9ebec207c8193754792076dc66eba9713 Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Tue, 19 Dec 2023 15:54:12 +0100
Subject: Added solutions for 15, 16, 17, 18 and 19

---
 2023/19/19b.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 2023/19/19b.c

(limited to '2023/19/19b.c')

diff --git a/2023/19/19b.c b/2023/19/19b.c
new file mode 100644
index 0000000..c7cecb6
--- /dev/null
+++ b/2023/19/19b.c
@@ -0,0 +1,98 @@
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define N 1000
+#define MAX(x,y) ((x)>(y)?(x):(y))
+
+typedef struct { int64_t val[26]; } part_t;
+typedef struct { char v, comp, wnext[10]; int64_t b; } rule_t;
+typedef struct { char name[50]; int64_t n; rule_t r[100]; } workflow_t;
+
+int64_t nw, A;
+workflow_t w[N];
+part_t p[N];
+
+workflow_t readw(char *buf) {
+	workflow_t ret = {0};
+	for (int i = 0; *buf != '{'; buf++, i++)
+		ret.name[i] = *buf;
+	for (rule_t r; *buf != '}'; ret.r[ret.n++] = r) {
+		buf++;
+		memset(&r, 0, sizeof(r));
+		if (*(buf+1) == '<' || *(buf+1) == '>') {
+			r.v = *buf;
+			r.comp = *(buf+1);
+			r.b = atoll(buf+2);
+			while (*buf != ':') buf++;
+			buf++;
+		}
+		for (int i = 0; *buf != ',' && *buf != '}'; buf++, i++)
+			r.wnext[i] = *buf;
+	}
+	return ret;
+}
+
+workflow_t findw(char *name) {
+	for (int i = 0; i < nw; i++)
+		if (!strcmp(name, w[i].name))
+			return w[i];
+	printf("Error: workflow %s not found\n", name);
+	exit(1);
+}
+
+int64_t work(workflow_t ww, int64_t lox, int64_t hix, int64_t lom, int64_t him,
+    int64_t loa, int64_t hia, int64_t los, int64_t his) {
+	if (lox > hix || lom > him || loa > hia || los > his)
+		return 0;
+
+	int64_t ret = 0;
+	for (int j = 0; j < ww.n; j++) {
+		int64_t lox1 = lox, hix1 = hix, lom1 = lom, him1 = him,
+			loa1 = loa, hia1 = hia, los1 = los, his1 = his;
+		rule_t r = ww.r[j];
+		switch (r.v) {
+		case 'x':
+			if (r.comp == '<') { hix1 = r.b-1; lox = r.b; }
+			else { lox1 = r.b+1, hix = r.b; }
+			break;
+		case 'm':
+			if (r.comp == '<') { him1 = r.b-1; lom = r.b; }
+			else { lom1 = r.b+1, him = r.b; }
+			break;
+		case 'a':
+			if (r.comp == '<') { hia1 = r.b-1; loa = r.b; }
+			else { loa1 = r.b+1, hia = r.b; }
+			break;
+		case 's':
+			if (r.comp == '<') { his1 = r.b-1; los = r.b; }
+			else { los1 = r.b+1, his = r.b; }
+			break;
+		default:
+			break;
+		}
+		ret += (r.wnext[0] == 'A' || r.wnext[0] == 'R') ?
+			MAX(0, hix1-lox1+1) * MAX(0, him1-lom1+1) *
+			    MAX(0, hia1-loa1+1) * MAX(0, his1-los1+1) *
+			    (r.wnext[0] == 'A')
+			:
+			work(findw(r.wnext), lox1, hix1,
+			    lom1, him1, loa1, hia1, los1, his1);
+	}
+
+	return ret;
+}
+
+int main() {
+	char *buf, line[N];
+
+	for (nw = 0; *(buf = fgets(line, N, stdin)) != '\n'; nw++)
+		w[nw] = readw(buf);
+
+	int64_t s = work(findw("in"), 1, 4000, 1, 4000, 1, 4000, 1, 4000);
+
+	printf("%" PRId64 "\n", s);
+	return 0;
+}
-- 
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