1 files changed, 87 insertions, 0 deletions

diff --git a/2023/19/19a.c b/2023/19/19a.c
new file mode 100644
index 0000000..81ee535
--- /dev/null
+++ b/2023/19/19a.c
@@ -0,0 +1,87 @@
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define N 1000
+
+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, np, 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;
+}
+
+part_t readp(char *buf) {
+        part_t p = {0};
+        while (*buf != '}') {
+                buf++;
+                p.val[*buf-'a'] = atoll(buf+2);
+                while(*buf != ',' && *buf != '}') buf++;
+        }
+        return p;
+}
+
+int64_t value(part_t p) {
+        return p.val['x'-'a'] + p.val['m'-'a'] + p.val['a'-'a'] + p.val['s'-'a'];
+}
+
+bool satisfy(part_t p, rule_t r) {
+        if (r.v == 0) return true;
+        int64_t val = p.val[r.v-'a'];
+        return r.comp == '<' ? (val < r.b) : (val > r.b);
+}
+
+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);
+}
+
+int main() {
+        char *buf, line[N];
+
+        for (nw = 0; *(buf = fgets(line, N, stdin)) != '\n'; nw++)
+                w[nw] = readw(buf);
+
+        for (np = 0; (buf = fgets(line, N, stdin)) != NULL; np++)
+                p[np] = readp(buf);
+
+        for (int i = 0; i < np; i++) {
+                workflow_t ww = findw("in");
+                for (rule_t r; ; ww = findw(r.wnext)) {
+                        for (int64_t j = 0; !satisfy(p[i], r = ww.r[j]); j++) ;
+                        if (!strcmp("A", r.wnext) || !strcmp("R", r.wnext)) {
+                                A += value(p[i]) * (r.wnext[0] == 'A');
+                                break;
+                        }
+                }
+        }
+
+        printf("%" PRId64 "\n", A);
+        return 0;
+}