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Code Issues Releases Wiki Activity

Added day 8

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This commit is contained in:
Chris Josten 2020-12-08 06:38:59 +01:00
parent a321a1a7b4
commit c138d30ea1
Signed by: chris
GPG key ID: 1795A594046530AB
4 changed files with 770 additions and 1 deletions
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2
source/app.d
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@ -14,6 +14,7 @@ import day4;
import day5;
import day6;
import day7;
import day8;
import dayutil;
immutable string progName = "aoc-2020";
@ -26,6 +27,7 @@ Variant function(int, File, bool, string[])[] programs = [
&day5.run,
&day6.run,
&day7.run,
&day8.run,
];
void printUsage(string name) {

154
source/day8.d Normal file
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@ -0,0 +1,154 @@
import std.array;
import std.algorithm;
import std.conv;
import std.range;
import std.stdio;
import std.string;
import std.traits;
import std.variant;
import dayutil;
Variant run(int part, File input, bool bigboy, string[] args) {
Instruction[] instructions = readInput(input.byLine);
Variant result = parts!int(part,
() => part1(instructions),
() => part2(instructions));
return result;
}
enum Memomic {
NOP,
ACC,
JMP
}
struct Instruction {
Memomic memomic;
int arg;
}
Instruction[] readInput(R)(R range) if (isInputRange!R && isSomeString!(ElementType!R)) {
return range.map!((text) {
Instruction instruction;
switch(text[0..3]) {
case "nop":
instruction.memomic = Memomic.NOP;
break;
case "acc":
instruction.memomic = Memomic.ACC;
break;
case "jmp":
instruction.memomic = Memomic.JMP;
break;
default:
writeln("unknown instruction: ", text[0..3]);
break;
}
//int sign = text[4] == '+' ? 1 : -1;
// to!int correctly handles + and -
instruction.arg = to!int(text[4..$]);
return instruction;
}).array;
}
int part1(ref Instruction[] instrs) {
int acc = 0;
int pc = 0;
int[] visited;
while(!visited.canFind(pc)) {
Instruction curInstr = instrs[pc];
writeln(pc, curInstr);
visited ~= [pc];
switch(curInstr.memomic) {
case Memomic.NOP:
pc += 1;
break;
case Memomic.ACC:
pc += 1;
acc += curInstr.arg;
break;
case Memomic.JMP:
pc += curInstr.arg;
break;
default:
break;
}
}
return acc;
}
unittest {
string input = q"EOS
nop +0
acc +1
jmp +4
acc +3
jmp -3
acc -99
acc +1
jmp -4
acc +6
EOS";
auto instrs = readInput(input.lineSplitter);
assert(part1(instrs) == 5);
}
int part2(ref Instruction[] instrs) {
bool finishes(ref Instruction[] instrs, out int acc) {
int pc = 0;
int[] visited;
while(!visited.canFind(pc)) {
Instruction curInstr = instrs[pc];
writeln(pc, curInstr);
visited ~= [pc];
switch(curInstr.memomic) {
case Memomic.NOP:
pc += 1;
break;
case Memomic.ACC:
pc += 1;
acc += curInstr.arg;
break;
case Memomic.JMP:
pc += curInstr.arg;
break;
default:
break;
}
if (pc == instrs.length) return true;
}
return false;
}
int acc;
// O(n^2) go brrr
for(size_t i = 0; i < instrs.length; i++) {
if (instrs[i].memomic == Memomic.ACC) continue;
Instruction[] dup = instrs.dup;
dup[i].memomic = dup[i].memomic == Memomic.NOP ? Memomic.JMP : Memomic.NOP;
if (finishes(dup, acc)) return acc;
}
return -1;
}
unittest {
string input = q"EOS
nop +0
acc +1
jmp +4
acc +3
jmp -3
acc -99
acc +1
jmp -4
acc +6
EOS";
auto instrs = readInput(input.lineSplitter);
assert(part2(instrs) == 8);
}