1 files changed, 77 insertions, 0 deletions

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;
+}