From 477ed667b1a9bc7f73850f45449666a8907ecaed Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Wed, 20 Dec 2023 16:32:41 +0100
Subject: Added solution for 20

---
 2023/20/graph.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 2023/20/graph.c

(limited to '2023/20/graph.c')

diff --git a/2023/20/graph.c b/2023/20/graph.c
new file mode 100644
index 0000000..bef0496
--- /dev/null
+++ b/2023/20/graph.c
@@ -0,0 +1,77 @@
+/* Picture generated with https://csacademy.com/app/graph_editor/ */
+
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define N 100
+#define ischar(c) (c >= 'a' && c <= 'z')
+
+typedef struct {
+	int nin, nout, in[N], out[N];
+	char name[20], outc[N][20];
+	bool isff, ison, reg[N];
+} node_t;
+
+char *buf, line[N][N];
+bool rx;
+int b, r, n;
+int64_t npush;
+node_t m[N];
+
+int findm(char *name) {
+	for (int k = 0; k < n; k++)
+		if (!strcmp(m[k].name, name))
+			return k;
+	return n;
+}
+
+int main() {
+	for (n = 0; (buf = fgets(line[n], N, stdin)) != NULL; n++) {
+		if (ischar(*buf)) b = n;
+		m[n].isff = *buf == '%';
+		if (!ischar(*buf)) buf++;
+		for (int i = 0; ischar(*buf); m[n].name[i++] = *(buf++)) ;
+		buf += 4;
+		for (int i = 0; *buf != '\n'; i++) {
+			while (!ischar(*buf)) buf++;
+			for (int j = 0; ischar(*buf); m[n].outc[i][j++] = *(buf++)) ;
+		}
+	}
+
+	for (int i = 0; i < n; i++) {
+		for (int j = 0; m[i].outc[j][0]; j++) {
+			int k = findm(m[i].outc[j]);
+			m[i].out[m[i].nout++] = k;
+			m[k].in[m[k].nin++] = i;
+			if (k == n) {
+				for (int k = 0; m[i].outc[j][k]; k++)
+					m[n].name[k] = m[i].outc[j][k];
+				n++;
+			}
+		}
+	}
+
+	for (int i = 0; i < n; i++)
+		if (!strcmp(m[i].name, "rx"))
+			r = i;
+
+/* Print adjacency list
+	printf("%d\n", n);
+	for (int i = 0; i < n; i++) {
+		printf("%d", m[i].nout);
+		for (int j = 0; j < m[i].nout; j++)
+			printf(" %d", m[i].out[j]);
+		printf("\n");
+	}
+	printf("broadcaster = %d, r = %d\n", b, r);
+*/
+
+	for (int i = 0; i < n; i++)
+		for (int j = 0; j < m[i].nout; j++)
+			printf("%d %d\n", i, m[i].out[j]);
+
+	return 0;
+}
-- 
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