1 files changed, 51 insertions, 0 deletions

diff --git a/2023/03/3a.c b/2023/03/3a.c
new file mode 100644
index 0000000..13c8c8d
--- /dev/null
+++ b/2023/03/3a.c
@@ -0,0 +1,51 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define N 1000
+
+bool isnum(char c) { return c >= '0' && c <= '9'; }
+bool issymbol(char c) { return c != '.' && c != 0 && c != '\n' && !isnum(c); }
+
+int grab(char *buf) {
+        int x;
+
+        if (!isnum(*buf))
+                return 0;
+
+        while (isnum(*buf)) buf--;
+        buf++;
+        x = atoi(buf);
+        while (isnum(*buf)) *buf++ = '.';
+
+        return x;
+}
+
+int main() {
+        char line[N], prev[N];
+        bool l, c, r, ul, uc, ur;
+        int i, sum;
+
+        sum = 0;
+        memset(line, '.', N);
+        memset(prev, '.', N);
+        while (fgets(&line[1], N-1, stdin) != NULL) {
+                for (i = 1; line[i]; i++) {
+                        l = issymbol(line[i-1]);
+                        c = issymbol(line[i]);
+                        r = issymbol(line[i+1]);
+                        ul = issymbol(prev[i-1]);
+                        uc = issymbol(prev[i]);
+                        ur = issymbol(prev[i+1]);
+                        if (l || r || ul || uc || ur)
+                                sum += grab(&line[i]);
+                        if (l || c || r)
+                                sum += grab(&prev[i]);
+                }
+                memcpy(prev, line, N);
+        }
+
+        printf("%d\n", sum);
+        return 0;
+}