summary refs log tree commit diff homepage
path: root/2020/day13.c
blob: a0e8c981c70b04b2f15a4a199ad822b6c9616267 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
int main(void) {
	int earliest = 0;
	scanf("%d\n", &earliest);
	int buses[128] = {0};
	int len = 0;
	for (;;) {
		int n = scanf("%d,", &buses[len]);
		if (!n) n = scanf("x,");
		if (n < 0) break;
		len++;
	}
	int min = INT_MAX;
	int bus = 0;
	for (int i = 0; i < len; ++i) {
		if (!buses[i]) continue;
		int wait = (earliest / buses[i] + 1) * buses[i] - earliest;
		if (wait < min) {
			min = wait;
			bus = buses[i];
		}
	}
	printf("%d\n", bus * min);
	long t = 0;
	long x = buses[0];
	for (int i = 1; i < len; ++i) {
		if (!buses[i]) continue;
		while ((t + i) % buses[i]) {
			t += x;
		}
		x *= buses[i];
	}
	printf("%ld\n", t);
}