question: seeBuildingsLeft

README.md

@@ -125,6 +125,7 @@ I started this in the [issue #176](https://buttondown.email/cassidoo/archive/we-
 - [361 - increasingSubsequence](src/2024/361-increasingSubsequence)
 - [368 - maxPairs](src/2024/368-maxPairs)
 - [377 - groupAnagrams](src/2024/377-groupAnagrams)
+- [378 - seeBuildingsLeft](src/2024/378-seeBuildingsLeft)
 </details>
 
 ## Installing & Running

src/2024/378-seeBuildingsLeft/README.md

@@ -0,0 +1,24 @@
+# seeBuildingsLeft
+
+Interview question of the [issue #378 of rendezvous with cassidoo](https://buttondown.com/cassidoo/archive/stand-for-something-or-you-will-fall-for-anything/).
+
+## The Question
+
+**Given a list of integers representing the heights of buildings, return the maximum number of buildings that can be seen when looking from the left. A building can see another building if it is taller than all the buildings to its left.** The height of the tallest building is included in the count.
+
+Example:
+
+```js
+seeBuildingsLeft([1,2,3,4,5])
+5
+
+seeBuildingsLeft([5,4,3,2,1])
+1
+
+seeBuildingsLeft([3,7,8,3,6,1])
+3
+```
+
+## Installing & Running
+
+Just `pnpm i` to install all dependencies and then `pnpm t` to run the tests!

src/2024/378-seeBuildingsLeft/seeBuildingsLeft.test.ts

@@ -0,0 +1,39 @@
+import { seeBuildingsLeft } from './seeBuildingsLeft';
+
+describe('#seeBuildingsLeft', () => {
+	it('returns the correct count for a strictly increasing list', () => {
+		expect(seeBuildingsLeft([1, 2, 3, 4, 5])).toBe(5);
+	});
+
+	it('returns the correct count for a strictly decreasing list', () => {
+		expect(seeBuildingsLeft([5, 4, 3, 2, 1])).toBe(1);
+	});
+
+	it('returns the correct count for a list with mixed values', () => {
+		expect(seeBuildingsLeft([3, 7, 8, 3, 6, 1])).toBe(3);
+	});
+
+	it('returns 1 for a list with all buildings of the same height', () => {
+		expect(seeBuildingsLeft([5, 5, 5, 5, 5])).toBe(1);
+	});
+
+	it('returns the correct count for a list with one building', () => {
+		expect(seeBuildingsLeft([10])).toBe(1);
+	});
+
+	it('returns the correct count for a list with some buildings taller after shorter ones', () => {
+		expect(seeBuildingsLeft([4, 3, 7, 6, 9, 2])).toBe(3);
+	});
+
+	it('returns the correct count when the tallest building is at the end of the list', () => {
+		expect(seeBuildingsLeft([1, 2, 3, 4, 10])).toBe(5);
+	});
+
+	it('returns the correct count for an empty list', () => {
+		expect(seeBuildingsLeft([])).toBe(0);
+	});
+
+	it('returns the correct count when there are zeros in the heights', () => {
+		expect(seeBuildingsLeft([0, 2, 0, 4, 6, 0, 8])).toBe(4);
+	});
+});

src/2024/378-seeBuildingsLeft/seeBuildingsLeft.ts

@@ -0,0 +1,27 @@
+/*
+Given a list of integers representing the heights of buildings,
+return the maximum number of buildings that can be seen when looking from the left.
+A building can see another building if it is taller than all the buildings to its left.
+The height of the tallest building is included in the count.
+
+Examples:
+
+seeBuildingsLeft([1,2,3,4,5])
+5
+
+seeBuildingsLeft([5,4,3,2,1])
+1
+
+seeBuildingsLeft([3,7,8,3,6,1])
+3
+*/
+
+export function seeBuildingsLeft(heights: number[]): number {
+	return heights.reduce(
+		({ count, maxHeight }, height) => ({
+			count: count + Number(height > maxHeight),
+			maxHeight: Math.max(height, maxHeight),
+		}),
+		{ count: 0, maxHeight: 0 },
+	).count;
+}