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Solve D04P02
+67
+67
day04/part2.ts
+67
day04/part2.ts
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import { readFileSync } from "fs";
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const grid = readFileSync("./input.txt", "utf8")
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.split(/\n/)
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.map((line) => line.trim().split(""));
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let totalRemovedRolls = 0;
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let numberOfAccessibleRolls;
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do {
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numberOfAccessibleRolls = 0;
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const removableRollsIndices: { r: number; c: number }[] = [];
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const countAdjacentRolls = (r: number, c: number) => {
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const directions = [
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{ dr: -1, dc: 0 },
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{ dr: -1, dc: 1 },
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{ dr: 0, dc: 1 },
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{ dr: 1, dc: 1 },
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{ dr: 1, dc: 0 },
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{ dr: 1, dc: -1 },
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{ dr: 0, dc: -1 },
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{ dr: -1, dc: -1 }
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];
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let numberOfAdjacentRolls = 0;
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for (const direction of directions) {
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const newR = r + direction.dr;
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const newC = c + direction.dc;
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if (
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newR >= 0 &&
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newR < grid.length &&
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newC >= 0 &&
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newC < grid[newR].length
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) {
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numberOfAdjacentRolls += grid[newR][newC] === "@" ? 1 : 0;
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}
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}
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return numberOfAdjacentRolls;
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};
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for (let r = 0; r < grid.length; r++) {
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for (let c = 0; c < grid[r].length; c++) {
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if (grid[r][c] === "@") {
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const numberOfAdjacentRolls = countAdjacentRolls(r, c);
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if (numberOfAdjacentRolls < 4) {
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numberOfAccessibleRolls++;
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removableRollsIndices.push({ r, c });
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}
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}
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}
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}
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totalRemovedRolls += numberOfAccessibleRolls;
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for (const { r, c } of removableRollsIndices) {
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grid[r][c] = ".";
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}
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} while (numberOfAccessibleRolls);
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console.log(totalRemovedRolls);