2022 Days 12 & 13 Complete!

2022/day12/problem

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+Advent of Code
+br0xen (AoC++) 26*
+
+--- Day 12: Hill Climbing Algorithm ---
+
+   You try contacting the Elves using your handheld device, but the river you're following must be
+   too low to get a decent signal.
+
+   You ask the device for a heightmap of the surrounding area (your puzzle input). The heightmap
+   shows the local area from above broken into a grid; the elevation of each square of the grid is
+   given by a single lowercase letter, where a is the lowest elevation, b is the next-lowest, and
+   so on up to the highest elevation, z.
+
+   Also included on the heightmap are marks for your current position (S) and the location that
+   should get the best signal (E). Your current position (S) has elevation a, and the location that
+   should get the best signal (E) has elevation z.
+
+   You'd like to reach E, but to save energy, you should do it in as few steps as possible. During
+   each step, you can move exactly one square up, down, left, or right. To avoid needing to get out
+   your climbing gear, the elevation of the destination square can be at most one higher than the
+   elevation of your current square; that is, if your current elevation is m, you could step to
+   elevation n, but not to elevation o. (This also means that the elevation of the destination
+   square can be much lower than the elevation of your current square.)
+
+   For example:
+
+ Sabqponm
+ abcryxxl
+ accszExk
+ acctuvwj
+ abdefghi
+
+   Here, you start in the top-left corner; your goal is near the middle. You could start by moving
+   down or right, but eventually you'll need to head toward the e at the bottom. From there, you
+   can spiral around to the goal:
+
+ v..v<<<<
+ >v.vv<<^
+ .>vv>E^^
+ ..v>>>^^
+ ..>>>>>^
+
+   In the above diagram, the symbols indicate whether the path exits each square moving up (^),
+   down (v), left (<), or right (>). The location that should get the best signal is still E, and .
+   marks unvisited squares.
+
+   This path reaches the goal in 31 steps, the fewest possible.
+
+   What is the fewest steps required to move from your current position to the location that should
+   get the best signal?
+
+   Your puzzle answer was 449.
+
+--- Part Two ---
+
+   As you walk up the hill, you suspect that the Elves will want to turn this into a hiking trail.
+   The beginning isn't very scenic, though; perhaps you can find a better starting point.
+
+   To maximize exercise while hiking, the trail should start as low as possible: elevation a. The
+   goal is still the square marked E. However, the trail should still be direct, taking the fewest
+   steps to reach its goal. So, you'll need to find the shortest path from any square at elevation
+   a to the square marked E.
+
+   Again consider the example from above:
+
+ Sabqponm
+ abcryxxl
+ accszExk
+ acctuvwj
+ abdefghi
+
+   Now, there are six choices for starting position (five marked a, plus the square marked S that
+   counts as being at elevation a). If you start at the bottom-left square, you can reach the goal
+   most quickly:
+
+ ...v<<<<
+ ...vv<<^
+ ...v>E^^
+ .>v>>>^^
+ >^>>>>>^
+
+   This path reaches the goal in only 29 steps, the fewest possible.
+
+   What is the fewest steps required to move starting from any square with elevation a to the
+   location that should get the best signal?
+
+   Your puzzle answer was 443.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+References
+
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