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author | June McEnroe <june@causal.agency> | 2018-12-07 12:32:44 -0500 |
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committer | June McEnroe <june@causal.agency> | 2020-11-22 00:14:25 -0500 |
commit | cbf6945921f8711d15cde6104d65ad586a17b1e6 (patch) | |
tree | d4af41432da8dc7d9b4c6303f7ec4392983bc701 /2018 | |
parent | Solve day 6 part 2 (diff) | |
download | aoc-cbf6945921f8711d15cde6104d65ad586a17b1e6.tar.gz aoc-cbf6945921f8711d15cde6104d65ad586a17b1e6.zip |
Solve day 7 part 1
Diffstat (limited to '')
-rw-r--r-- | 2018/day07.c | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/2018/day07.c b/2018/day07.c new file mode 100644 index 0000000..43dd786 --- /dev/null +++ b/2018/day07.c @@ -0,0 +1,27 @@ +#include <stdio.h> +#include <stdlib.h> + +typedef unsigned uint; + +int main() { + uint steps = 0; + uint deps[26] = {0}; + while (!feof(stdin)) { + char dep, step; + scanf( + "Step %c must be finished before step %c can begin.\n", + &dep, &step + ); + deps[step - 'A'] |= 1 << (dep - 'A'); + } + while (steps != (1 << 26) - 1) { + for (uint i = 0; i < 26; ++i) { + if (steps & (1 << i)) continue; + if ((deps[i] & steps) != deps[i]) continue; + printf("%c", 'A' + i); + steps |= (1 << i); + break; + } + } + printf("\n"); +} |