advent2025

commit 1580b3c4c755f07896b0ef742b72d5a6f11ab539
parent 47634b6c8a003dbee3444f5521e3a40dc433ae53
Author: bsandro <email@bsandro.tech>
Date:   Tue,  2 Dec 2025 08:59:48 +0200

day02 p2

Diffstat:
M
day02.c
 | 
40
+++++++++++++++++++++++++++++++++-------

1 file changed, 33 insertions(+), 7 deletions(-)
diff --git a/day02.c b/day02.c
@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <inttypes.h>
 #include <math.h>
+#include <string.h>
 #include "cputime.h"
 
 typedef struct Range {
@@ -8,17 +9,26 @@ typedef struct Range {
     uint64_t last;
 } Range;
 
+inline int digits(uint64_t num) {
+    return log10l(num)+1;
+}
+
 inline uint64_t btoi(uint64_t buf[32], int bufs) {
     uint64_t num = 0;
     for (int i=0;i<bufs;++i) num = num*10+buf[i];
     return num;
 }
 
-inline int digits(uint64_t num) {
-    return log10l(num)+1;
+inline void itoa(uint64_t num, char str[32]) { //unused
+    int d = digits(num);
+    for (int i=0;i<d;++i) {
+        str[i] = num%10+'0';
+    }
+    str[d] = '\0';
+    printf("itoa %lu -> %s\n", num, str);
 }
 
-inline bool is_silly(uint64_t num) {
+inline bool is_silly1(uint64_t num) {
     int d = digits(num);
     if (d%2==0) {
         long shift = powl(10, d/2);
@@ -29,10 +39,24 @@ inline bool is_silly(uint64_t num) {
     return false;
 }
 
-inline uint64_t sum_silly(Range range) {
+inline bool is_silly2(uint64_t num) {
+    int d = digits(num);
+    char s[32] = {0};
+    snprintf(s, 31, "%lu", num); // gave up on atoi for now
+    for (int i=1;i<=d/2;++i) { // checking pattern 0-i
+        int rep = 0;
+        for (int j=0;j<d;j+=i) {
+            rep |= strncmp(s, s+j, i);
+        }
+        if (rep==0) return true;
+    }
+    return false;
+}
+
+inline uint64_t sum_silly(Range range, bool (*check_silly)(uint64_t)) {
     uint64_t sum = 0;
     for (uint64_t i=range.first;i<=range.last;++i) {
-        if (is_silly(i)) sum+=i;
+        if (check_silly(i)) sum+=i;
     }
     return sum;
 }
@@ -42,6 +66,7 @@ int main(void) {
     int bufs = 0;
     Range range = {0};
     uint64_t p1 = 0;
+    uint64_t p2 = 0;
     for (int c=getchar();c!=EOF;c=getchar()) {
         if (c>='0'&&c<='9') {
             buf[bufs++] = c-'0';
@@ -52,9 +77,10 @@ int main(void) {
             range.last = btoi(buf, bufs);
             bufs = 0;
             //printf("%"PRIu64"->%"PRIu64"\n", range.first, range.last);
-            p1 += sum_silly(range);
+            p1 += sum_silly(range, is_silly1);
+            p2 += sum_silly(range, is_silly2);
         }
     }
-    printf("p1: %" PRIu64 "\n", p1);
+    printf("p1: %" PRIu64 "\np2: %" PRIu64 "\n", p1, p2);
     return 0;
 }