AoC 2024 - Day 09 (part I solution)

2024/ts/day-09/code.ts

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+// Solution for day 9 of advent of code 2024
+
+import { readInputLines, readInput } from "../system/aoc-helper";
+import "../utils/array-helpers";
+import { Puzzle } from "../model/puzzle";
+
+const processInput = (day: number) => {
+    const line = readInput(day);
+    return line.split("").map(c => parseInt(c, 10));
+};
+
+type DiskBlock = '.' | number;
+
+const explode = (diskMap: number[]) => {
+    const length = diskMap.sum();
+    const result: DiskBlock[] = Array(length).fill('.');
+    let fileIndex = 0;
+    let diskIndex = 0;
+    let fileIndicator = true;
+    for (const size of diskMap) {
+        if (fileIndicator) {
+            result.fill(fileIndex, diskIndex, diskIndex + size);
+            fileIndex += 1;
+            fileIndicator = false;
+        } else {
+            result.fill('.', diskIndex, diskIndex + size);
+            fileIndicator = true;
+        }
+        diskIndex += size;
+    }
+    return result;
+};
+
+const partOne = (input: number[], debug: boolean) => {
+    const disk = explode(input);
+    let lastBlockIndex = disk.length - 1;
+    while (disk[lastBlockIndex] === '.') {
+        lastBlockIndex -= 1;
+    }
+    let firstEmptyIndex = 0;
+    while (disk[firstEmptyIndex] !== '.') {
+        firstEmptyIndex += 1;
+    }
+    while (firstEmptyIndex < lastBlockIndex) {
+        disk[firstEmptyIndex] = disk[lastBlockIndex];
+        disk[lastBlockIndex] = '.';
+        while (disk[lastBlockIndex] === '.') {
+            lastBlockIndex -= 1;
+        }
+        while (disk[firstEmptyIndex] !== '.') {
+            firstEmptyIndex += 1;
+        }
+    }
+
+    const checksum = disk.sum((item, index) => (item === '.') ? 0 : item * index);
+    return checksum;
+};
+
+const partTwoCalculated = (input: number[], debug: boolean) => {
+    const disk = explode(input);
+    const files = input.filter((_, index) => index % 2 === 0);
+    const blocks = files.slice();
+    const empties = input.filter((_, index) => index % 2 === 1);
+    for (let findex = files.length-1; findex > 0; findex -= 1) {
+        const fileSize = files[findex];
+        const eindex = empties.findIndex(empty => empty >= fileSize);
+        if (eindex === -1) {
+            continue;
+        }
+        const emptySize = empties[eindex];
+        const emptyStart = blocks.slice(0, eindex+1).sum() + empties.slice(0, eindex).sum();
+        const fileStart = blocks.slice(0, findex).sum() + empties.slice(0, findex).sum();
+        for (let i = 0; i < fileSize; i++) {
+            disk[emptyStart + i] = disk[fileStart + i];
+            disk[fileStart + i] = '.';
+        }
+        empties[eindex] = emptySize - fileSize;
+        blocks[eindex] += fileSize;
+        // console.log(disk.join(""));
+        // console.log(files);
+        // console.log(blocks);
+        // console.log(empties);
+    }
+    //console.log(disk.join(""));
+    const checksum = disk.sum((item, index) => (item === '.') ? 0 : item * index);
+    return checksum;
+};
+
+const partTwo = (input: number[], debug: boolean) => {
+    const disk = explode(input);
+    let lastBlockIndex = disk.length - 1;
+    while (disk[lastBlockIndex] === '.') {
+        lastBlockIndex -= 1;
+    }
+    let firstEmptyIndex = 0;
+    while (disk[firstEmptyIndex] !== '.') {
+        firstEmptyIndex += 1;
+    }
+    while (firstEmptyIndex < lastBlockIndex) {
+        disk[firstEmptyIndex] = disk[lastBlockIndex];
+        disk[lastBlockIndex] = '.';
+        while (disk[lastBlockIndex] === '.') {
+            lastBlockIndex -= 1;
+        }
+        while (disk[firstEmptyIndex] !== '.') {
+            firstEmptyIndex += 1;
+        }
+    }
+
+    const checksum = disk.sum((item, index) => (item === '.') ? 0 : item * index);
+    return checksum;
+};
+
+const resultOne = (_: any, result: number) => {
+    return `Result part one is ${result}`;
+};
+
+const resultTwo = (_: any, result: number) => {
+    return `Result part two is ${result}`;
+};
+
+const showInput = (input: number[]) => {
+    console.log(input);
+};
+
+const test = (_: number[]) => {
+    console.log("----Test-----");
+};
+
+export const solution: Puzzle<number[], number> = {
+    day: 9,
+    input: () => processInput(9),
+    partOne,
+    partTwo,
+    resultOne: resultOne,
+    resultTwo: resultTwo,
+    showInput,
+    test,
+}