81 lines
2.1 KiB
TypeScript
81 lines
2.1 KiB
TypeScript
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import { readMap, mapFind, Guard, moveGuard, displayMap, mapForEach, Dir, EMPTY, Pos } from "./solve_1.ts";
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function getMDir(
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dir: Dir,
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mapValue: string
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){
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if (mapValue === "+") {
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return mapValue;
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}
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if (dir === mapValue || mapValue === EMPTY){
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return dir;
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}
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return "+";
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}
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function loopDetect(
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obstaclePos: Pos,
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guard: Guard,
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map: string[][]
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){
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map[obstaclePos.y][obstaclePos.x] = "#";
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try {
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let doubleMoveGaurd: Guard | "out" = guard;
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for(;;){
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const n = moveGuard(guard, map);
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if (n === "out"){
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return false;
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}
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guard = n;
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doubleMoveGaurd = moveGuard(doubleMoveGaurd, map);
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if (doubleMoveGaurd === "out"){
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return false;
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}
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doubleMoveGaurd = moveGuard(doubleMoveGaurd, map);
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if (doubleMoveGaurd === "out"){
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return false;
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}
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if (guard.pos.x === doubleMoveGaurd.pos.x && guard.pos.y === doubleMoveGaurd.pos.y
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&& guard.direction === doubleMoveGaurd.direction
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){
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return true;
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}
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}
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}
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finally {
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map[obstaclePos.y][obstaclePos.x] = ".";
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}
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}
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if (import.meta.main) {
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const map = await readMap("input.txt");
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const guardPos = mapFind(map, (_x, _y, value) => value === "^");
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if (!guardPos) {
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throw new Error("Guard not found");
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}
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const { x, y } = guardPos;
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let guard: Guard = {
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pos: { x, y },
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direction: "N",
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};
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map[y][x] = "|"
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let count = 0;
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for (;;) {
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const n = moveGuard(guard, map);
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if (n === "out") {
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break;
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}
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if (map[n.pos.y][n.pos.x] === EMPTY){
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if (loopDetect(n.pos, guard, map)){
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console.log(n.pos);
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count++;
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}
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}
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guard = n;
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const v = map[guard.pos.y][guard.pos.x];
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map[guard.pos.y][guard.pos.x] = getMDir(guard.direction, v);
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}
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displayMap(map);
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console.log(count);
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}
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