From 1939c709bdfeeae9dad00a989c71ef704d5154c4 Mon Sep 17 00:00:00 2001 From: Timothy Warren Date: Fri, 9 Dec 2022 11:20:30 -0500 Subject: [PATCH] Update README for day 8 part 2 --- day8/README.md | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/day8/README.md b/day8/README.md index 4c01488..7b70a63 100644 --- a/day8/README.md +++ b/day8/README.md @@ -31,3 +31,43 @@ All of the trees around the edge of the grid are **visible** - since they are al 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?** + +## Part 2 + +Content with the amount of tree cover available, the Elves just need to know the best spot to build their tree house: they would like to be able to see a lot of trees. + +To measure the viewing distance from a given tree, look up, down, left, and right from that tree; stop if you reach an edge or at the first tree that is the same height or taller than the tree under consideration. (If a tree is right on the edge, at least one of its viewing distances will be zero.) + +The Elves don't care about distant trees taller than those found by the rules above; the proposed tree house has large eaves to keep it dry, so they wouldn't be able to see higher than the tree house anyway. + +In the example above, consider the middle 5 in the second row: + + 30373 + 25512 + 65332 + 33549 + 35390 + +* Looking up, its view is not blocked; it can see 1 tree (of height 3). +* Looking left, its view is blocked immediately; it can see only 1 tree (of height 5, right next to it). +* Looking right, its view is not blocked; it can see 2 trees. +* Looking down, its view is blocked eventually; it can see 2 trees (one of height 3, then the tree of height 5 that blocks its view). + +A tree's scenic score is found by multiplying together its viewing distance in each of the four directions. For this tree, this is 4 (found by multiplying 1 * 1 * 2 * 2). + +However, you can do even better: consider the tree of height 5 in the middle of the fourth row: + + 30373 + 25512 + 65332 + 33549 + 35390 + +* Looking up, its view is blocked at 2 trees (by another tree with a height of 5). +* Looking left, its view is not blocked; it can see 2 trees. +* Looking down, its view is also not blocked; it can see 1 tree. +* Looking right, its view is blocked at 2 trees (by a massive tree of height 9). + +This tree's scenic score is 8 (2 * 2 * 1 * 2); this is the ideal spot for the tree house. + +Consider each tree on your map. What is the highest scenic score possible for any tree? \ No newline at end of file