An expedition of Elves comes across a peculiar patch of tall trees all planted carefully in a grid. The Elves explain that a previous expedition planted these trees as a reforestation effort. Now, they're curious if this would be a good location for a tree house.
First, determine whether there is enough tree cover here to keep a tree house hidden. To do this, you need to count the number of trees that are visible from outside the grid when looking directly along a row or column.
The Elves have already launched a quadcopter to generate a map with the height of each tree (your puzzle input). For example:
#################
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### ###
### 30373 ###
### 25512 ###
### 65332 ###
### 33549 ###
### 35390 ###
### ###
#################
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Each tree is represented as a single digit whose value is its height, where 0 is the shortest and 9 is the tallest.
A tree is visible if all of the other trees between it and an edge of the grid are shorter than it. Only consider trees in the same row or column; that is, only look up, down, left, or right from any given tree.
All of the trees around the edge of the grid are visible - since they are already on the edge, there are no trees to block the view. In this example, that only leaves the interior nine trees to consider:
The top-left 5 is visible from the left and top. (It isn't visible from the right or bottom since other trees of height 5 are in the way.)
The top-middle 5 is visible from the top and right.
The top-right 1 is not visible from any direction; for it to be visible, there would need to only be trees of height 0 between it and an edge.
The left-middle 5 is visible, but only from the right.
The center 3 is not visible from any direction; for it to be visible, there would need to be only trees of at most height 2 between it and an edge.
The right-middle 3 is visible from the right.
In the bottom row, the middle 5 is visible, but the 3 and 4 are not.
With 16 trees visible on the edge and another 5 visible in the interior, a total of 21 trees are visible in this arrangement.
Consider your map; how many trees are visible from outside the grid?
def count_trees(trees):
return Noneimport numpy as np
import codewars_test as test
@test.describe("Fixed Tests")
def basic_tests():
@test.it('Basic Test Cases')
def basic_test_cases():
test.assert_equals(count_trees(np.array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])), 9)
test.assert_equals(count_trees(np.array([[1, 2, 3],
[4, 1, 6],
[7, 8, 9]])), 8)
test.assert_equals(count_trees(np.array([[3, 3, 3, 3, 3],
[4, 4, 4, 4, 4],
[2, 2, 2, 2, 2],
[5, 5, 5, 5, 5]])), 17)
test.assert_equals(count_trees(np.array([[3, 0, 3, 7, 3],
[2, 5, 5, 1, 2],
[6, 5, 3, 3, 2],
[3, 3, 5, 4, 9],
[3, 5, 3, 9, 0]])), 21)