Day6 C

day6/c/day6.c

@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+#define LINE_MAX_LENGTH 256
+#define MAX_TIMES 16
+#define NUM_0_CHARCODE 48
+#define NUM_9_CHARCODE NUM_0_CHARCODE + 9
+
+int score(int max_duration, int hold_duration);
+
+int main() {
+    char *p, *buf, c;
+
+    buf = (char *)malloc(LINE_MAX_LENGTH);
+    memset(buf, 0, LINE_MAX_LENGTH);
+    p = buf;
+
+    unsigned long first = 1;
+    unsigned long times[MAX_TIMES], times_num = 0;
+    unsigned long records[MAX_TIMES], records_num = 0;
+
+    while ((c = getchar()) != EOF) {
+        *p++ = c;
+        if (c == '\n') {
+            p = buf;
+            while (*p != '\n') {
+                while (*p < NUM_0_CHARCODE || *p > NUM_9_CHARCODE) p++;
+
+                if (first) {
+                    sscanf(p, "%lu", &times[times_num]);
+                    times_num++;
+                } else {
+                    sscanf(p, "%lu", &records[records_num]);
+                    records_num++;
+                }
+
+                while (*p >= NUM_0_CHARCODE && *p <= NUM_9_CHARCODE) p++;
+            }
+
+            if (first) {
+                first = 0;
+            }
+            memset(buf, 0, LINE_MAX_LENGTH);
+            p = buf;
+        }
+    }
+
+    // Part 1
+    unsigned long part1 = 1;
+    for (unsigned long i = 0; i < times_num; i++) {
+        // quick mafs
+        unsigned long min_d = (unsigned long)ceil((times[i] - sqrt(times[i] * times[i] - 4 * (records[i]+1))) / 2);
+        unsigned long max_d = (unsigned long)floor((times[i] + sqrt(times[i] * times[i] - 4 * (records[i]+1))) / 2);
+        part1 *= (max_d - min_d + 1);
+    }
+
+    printf("%lu\n", part1);
+
+    free(buf);
+}
+
+int score(int max_duration, int hold_duration) {
+    return hold_duration * (max_duration - hold_duration);
+}

day6/input.txt

@@ -0,0 +1,2 @@
+Time:        41     66     72     66
+Distance:   244   1047   1228   1040

day6/input2.txt

@@ -0,0 +1,2 @@
+Time:        41667266
+Distance:   244104712281040

day6/sample.txt

@@ -0,0 +1,2 @@
+Time:      7  15   30
+Distance:  9  40  200