Solve 2025-04

2025/04/2025-04.run.xml

@@ -0,0 +1,7 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="2025-04" type="BunRunConfiguration">
+    <option name="program" value="2025/04/run.ts" />
+    <option name="workingDirectory" value="$PROJECT_DIR$" />
+    <method v="2" />
+  </configuration>
+</component>

2025/04/index.test.ts

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+import { describe, expect, it } from 'bun:test';
+import { solveFirst, solveSecond } from './index.ts';
+
+describe('2025-04', () => {
+  const testInput = `..@@.@@@@.
+@@@.@.@.@@
+@@@@@.@.@@
+@.@@@@..@.
+@@.@@@@.@@
+.@@@@@@@.@
+.@.@.@.@@@
+@.@@@.@@@@
+.@@@@@@@@.
+@.@.@@@.@.`;
+  it('first', () => {
+    expect(solveFirst(testInput)).toBe(13);
+  });
+  it('second', () => {
+    expect(solveSecond(testInput)).toBe(43);
+  });
+});

2025/04/index.ts

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+import { replaceChar } from '../../utils/array.ts';
+import { findCoordsOfDigit, getAdjacent } from '../../utils/coordinates.ts';
+
+const PAPER_ROLL = '@';
+export function solveFirst(input: string): number {
+  const rows = input.split('\n');
+
+  const rolls = findCoordsOfDigit(rows, PAPER_ROLL).filter(
+    ([x, y]) =>
+      Object.values(getAdjacent(rows, x, y)).filter((n) => n === PAPER_ROLL)
+        .length < 4
+  );
+  return rolls.length;
+}
+
+export function solveSecond(input: string): number {
+  const rows = input.split('\n');
+
+  let removed = 0;
+
+  let removedInStep = 0;
+  do {
+    removedInStep = 0;
+    findCoordsOfDigit(rows, PAPER_ROLL).forEach(([x, y]) => {
+      if (
+        Object.values(getAdjacent(rows, x, y)).filter((n) => n === PAPER_ROLL)
+          .length < 4
+      ) {
+        removedInStep++;
+        replaceChar(rows, x, y, 'X');
+      }
+    });
+    removed += removedInStep;
+  } while (removedInStep > 0);
+
+  return removed;
+}

2025/04/run.ts

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+import { join } from 'path';
+import { solveFirst, solveSecond } from './index.ts';
+
+const input = await Bun.file(join(__dirname, 'input.txt')).text();
+
+const firstAnswer = solveFirst(input);
+
+console.log(firstAnswer);
+
+const secondAnswer = solveSecond(input);
+
+console.log(secondAnswer);