committing everything squashed

03/part1.c

@@ -0,0 +1,71 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#define LINELENGTH 150
+#define NEXT(X) ((X + 3 + 1) % 3)
+#define PREV(X) ((X + 3 - 1) % 3)
+
+/* I wish I had python generator or Go coroutine... */
+#define STATE_BEGIN 0
+#define STATE_READING 1
+#define STATE_END 2
+int read_state = STATE_BEGIN;
+
+/* Return at least 3 lines; first and last lines and first chars are all '.' */
+char* readline(char* buf, int max_size) {
+    switch (read_state) {
+        case STATE_BEGIN:
+            memset(buf, '.', max_size);
+            buf[max_size - 2] = '\n';
+            buf[max_size - 1] = '\0';
+            read_state = STATE_READING;
+            return buf;
+        case STATE_READING:
+            buf[0] = '.';
+            if (!fgets(buf + 1, max_size, stdin)) {
+                memset(buf, '.', max_size);
+                buf[max_size - 2] = '\n';
+                 buf[max_size - 1] = '\0';
+                read_state = STATE_END;
+            }
+            return buf;
+        case STATE_END:
+            return NULL;
+    }
+}
+
+#define IS_SYMBOL(X) ((X < '0' || X > '9') && X != '.' && X != '\n')
+#define IS_ADJACENT_SYMBOL(buf, i, j) ( \
+        IS_SYMBOL(buf[i][j - 1]) || IS_SYMBOL(buf[i][j + 1]) || \
+        IS_SYMBOL(buf[PREV(i)][j]) || IS_SYMBOL(buf[NEXT(i)][j]) || \
+        IS_SYMBOL(buf[PREV(i)][j - 1]) || IS_SYMBOL(buf[PREV(i)][j + 1]) || \
+        IS_SYMBOL(buf[NEXT(i)][j - 1]) || IS_SYMBOL(buf[NEXT(i)][j + 1]))
+    
+int main(void) {
+    char buf[3][LINELENGTH];
+    int sum = 0;
+    
+    readline(buf[0], LINELENGTH);
+    readline(buf[1], LINELENGTH);
+    for (int i = 1; readline(buf[NEXT(i)], LINELENGTH); i = NEXT(i)) {
+        bool is_part = false;
+        int num = 0;
+
+        for (int j = 1; buf[i][j]; j++) {  // j = 0 is '.' guard
+            if (buf[i][j] >= '0' && buf[i][j] <= '9') {
+                num = num * 10 + (buf[i][j] - '0');
+                is_part = is_part || IS_ADJACENT_SYMBOL(buf, i, j);
+            } else {
+                sum += is_part ? num : 0;
+                is_part = false;
+                num = 0;
+            }
+        }
+    }
+
+    printf("%d\n", sum);
+    return 0;
+}
+