Solve 2024-09 (partly)

2024/09/index.ts

@@ -0,0 +1,120 @@
+import { sumArray } from '../../utils/array.ts';
+
+export function solveFirst(input: string): number {
+  const finalPositions = decompressInput(input);
+
+  let l = 0;
+  let r = finalPositions.length - 1;
+  while (l < r) {
+    if (finalPositions[l] !== -1) {
+      l++;
+      continue;
+    }
+
+    if (finalPositions[r] === -1) {
+      r--;
+      continue;
+    }
+
+    finalPositions[l] = finalPositions[r];
+    finalPositions[r] = -1;
+    l++;
+    r--;
+  }
+
+  return sumArray(finalPositions.map((v, i) => (v > 0 ? v * i : 0)));
+}
+
+function decompressInput(input: string) {
+  const len = input.length;
+  const finalPositions: number[] = [];
+
+  for (let i = 0; i < len; i++) {
+    const amount = Number(input[i]);
+
+    const id = i % 2 === 0 ? Math.floor(i / 2) : -1;
+    for (let j = 0; j < amount; j++) {
+      finalPositions.push(id);
+    }
+  }
+  return finalPositions;
+}
+
+function getSpaceMap(memory: number[]) {
+  const spaces = Array.from({ length: 10 }, () => [] as number[]);
+
+  let i = 0;
+  while (i < memory.length) {
+    if (memory[i] >= 0) {
+      // not a space
+      i++;
+      continue;
+    }
+
+    let size = 0;
+    while (memory[i] < 0) {
+      size++;
+      i++;
+    }
+
+    // push start position
+    spaces[size].push(i - size);
+  }
+
+  return spaces;
+}
+
+export function solveSecond(input: string): number {
+  const finalPositions = decompressInput(input);
+  const spaces = getSpaceMap(finalPositions);
+
+  // TODO: theres bug in her somewhere
+
+  let moved: number[] = [];
+  let r = finalPositions.length - 1;
+  while (r > 0) {
+    if (finalPositions[r] < 0) {
+      // spaces can't be moved
+      r--;
+      continue;
+    }
+
+    let size = 0;
+    const id = finalPositions[r];
+    while (finalPositions[r] === id) {
+      r--;
+      size++;
+    }
+
+    const firstFreeSpaceSize = spaces.findIndex(
+      (sp, si) => si >= size && sp.length > 0 && sp[0] < r
+    );
+
+    if (firstFreeSpaceSize < 0) {
+      continue;
+    }
+
+    const spaceIdx = spaces[firstFreeSpaceSize].shift()!;
+
+    if (moved.includes(id)) {
+      continue;
+    }
+    moved.push(id);
+    for (let i = 0; i < size; i++) {
+      finalPositions[r + i + 1] = -1;
+      finalPositions[spaceIdx + i] = id;
+    }
+
+    const spaceDiff = firstFreeSpaceSize - size;
+    if (spaceDiff > 0) {
+      spaces[spaceDiff].push(spaceIdx + firstFreeSpaceSize - spaceDiff);
+      spaces[spaceDiff].sort((a, b) => a - b);
+    }
+
+    // r = position;
+  }
+
+  // console.log(finalPositions);
+
+  return sumArray(finalPositions.map((v, i) => (v > 0 ? v * i : 0)));
+}