advent2019

commit 1abca040b7e39f5ab2f8fc5799071195442d866e
parent 44696ec42c0aebc2ccc5fc61f13a7ff143657a5a
Author: bsandro <email@bsandro.tech>
Date:   Sun,  7 Dec 2025 00:42:00 +0200

Day 01

Diffstat:
A
cputime.h
 | 
12
++++++++++++
A
day01.c
 | 
34
++++++++++++++++++++++++++++++++++

2 files changed, 46 insertions(+), 0 deletions(-)
diff --git a/cputime.h b/cputime.h
@@ -0,0 +1,12 @@
+#pragma once
+#include <time.h>
+static volatile double time_started = 0;
+
+void __attribute((constructor)) begin() {
+    time_started = clock();
+}
+
+void __attribute((destructor)) end() {
+    double elapsed = clock() - time_started;
+    printf("Elapsed: %f s\n", elapsed/CLOCKS_PER_SEC);
+}
diff --git a/day01.c b/day01.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <inttypes.h>
+#include "cputime.h"
+
+typedef struct {
+    char data[16];
+    int len;
+} Buffer;
+
+int btoi(Buffer buf) {
+    int num = 0;
+    for (int i=0;i<buf.len;++i) num = num*10+buf.data[i];
+    return num;
+}
+
+int main(void) {
+    Buffer buf = {0};
+    uint64_t p1 = 0;
+    uint64_t p2 = 0;
+    for (int c=getchar();c!=EOF;c=getchar()) {
+        if (c>='0'&&c<='9') {
+            buf.data[buf.len++] = c-'0';
+        } else {
+            int num = btoi(buf);
+            buf.len = 0;
+            p1 += num/3-2;
+            for (int fuel=num/3-2; fuel>0; fuel=fuel/3-2) {
+                p2 += fuel;
+            }
+        }
+    }
+    printf("p1: %"PRIu64"\np2: %"PRIu64"\n", p1, p2);
+    return 0;
+}