2018-1: Oh Say Can You See?
Imagine standing in front of a line of skyscrapers of varying heights. Assume that you can always see a skyscraper that is taller than a closer skyscraper. For example, a person on the left of the diagram below can see 3 skyscrapers – the first, fourth, and sixth from left to right. In contrast, a person on the right can see 2 skyscrapers – the seventh and sixth.
┌───┐
│ │
│ │
│ │
│ │
┌───┐ │ │ ┌───┐
│ │ │ │ │ │
│ │ │ │ │ │
│ │ │ │ │ │
│ │ │ │ │ │
┌───┐ ┌───┐ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │
│ │ │ │ │ │ ┌───┐ │ │ │ │
│ │ │ │ ┌───┐ │ │ │ │ │ │ │ │
│ │ │ │ │ │ │ │ │ │ │ │ │ │
│ 5 │ │ 5 │ │ 2 │ │ 10 │ │ 3 │ │ 15 │ │ 10 │
─┘ └──┘ └──┘ └──┘ └──┘ └──┘ └──┘ └─
Write an APL function that, given a scalar or vector of skyscraper heights from closest to furthest, will return an integer representing the number of skyscrapers that can be seen.
Examples:
(your_function) 5 5 2 10 3 15 10 ⍝ from the left person's view
3
(your_function) ⌽ 5 5 2 10 3 15 10 ⍝ from the right person's view
2
(your_function) ⍬ ⍝ no skyscrapers here!
0
(your_function) 10 ⍝ single skyscraper
1
your_function ←
Solutions
