mirror of
https://github.com/HenkKalkwater/aoc-2020
synced 2024-12-22 16:35:18 +00:00
Brute forcing does not work
This commit is contained in:
parent
fb9815b6ec
commit
f013067d26
|
@ -7,8 +7,9 @@ struct ParsedInput {
|
|||
|
||||
Variant run(int part, File input, bool bigboy, string[] args) {
|
||||
ParsedInput pInput = input.byLineCopy.array.parseInput();
|
||||
Variant result = parts!int(part,
|
||||
() => part1(pInput));
|
||||
Variant result = parts!long(part,
|
||||
() => part1(pInput),
|
||||
() => part2(pInput, 100000000000000));
|
||||
return result;
|
||||
}
|
||||
|
||||
|
@ -17,17 +18,15 @@ Variant run(int part, File input, bool bigboy, string[] args) {
|
|||
ParsedInput input;
|
||||
input.timestamp = to!int(range[0]);
|
||||
|
||||
input.busses = range[1].splitter(',').filter!(c => c != "x").map!(to!int).array;
|
||||
input.busses = range[1].splitter(',').map!(c => c == "x" ? -1 : c.to!int).array;
|
||||
writeln(input);
|
||||
return input;
|
||||
}
|
||||
|
||||
int part1(ParsedInput input) {
|
||||
import std.math;
|
||||
|
||||
int earliestBus = 0;
|
||||
int earliestBusTimestamp = int.max;
|
||||
foreach(int bus; input.busses) {
|
||||
foreach(int bus; input.busses.filter!(x => x != -1)) {
|
||||
int closestTimestamp = (input.timestamp / bus + 1 ) * bus;
|
||||
writeln(closestTimestamp);
|
||||
if (closestTimestamp < earliestBusTimestamp) {
|
||||
|
@ -35,10 +34,45 @@ int part1(ParsedInput input) {
|
|||
earliestBus = bus;
|
||||
}
|
||||
}
|
||||
writefln("Bus %d at %d", earliestBus, earliestBusTimestamp);
|
||||
// debug writefln("Bus %d at %d", earliestBus, earliestBusTimestamp);
|
||||
return earliestBus * (earliestBusTimestamp - input.timestamp);
|
||||
}
|
||||
|
||||
long part2(ParsedInput input) {
|
||||
long result = 0;
|
||||
|
||||
long startI = startFrom == 0 ? 0 : startFrom / input.busses[0];
|
||||
|
||||
for (long i = startI; result == 0; i++) {
|
||||
long offset = i * input.busses[0];
|
||||
bool fail = false;
|
||||
|
||||
foreach(j, subsequentBus; input.busses[1..$].enumerate(1)) {
|
||||
if (subsequentBus == -1) continue;
|
||||
|
||||
if ((offset + j) % subsequentBus != 0) {
|
||||
fail = true;
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
if (!fail) {
|
||||
result = offset;
|
||||
}
|
||||
|
||||
debug {
|
||||
if (i % 10000 == 0) {
|
||||
writef("\rAt %d", offset);
|
||||
stdout.flush();
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
debug writeln();
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
unittest {
|
||||
string[] input = [
|
||||
"939",
|
||||
|
@ -48,4 +82,5 @@ unittest {
|
|||
ParsedInput pInput = parseInput(input);
|
||||
|
||||
assert(part1(pInput) == 295);
|
||||
assert(part2(pInput) == 1068781);
|
||||
}
|
||||
|
|
Loading…
Reference in a new issue