The lava starts flowing rapidly once the Lava Production Facility is operational. As you leave, the reindeer offers you a parachute, allowing you to quickly reach Gear Island. As you descend, your bird's-eye view of Gear Island reveals why you had trouble finding anyone on your way up: half of Gear Island is empty, but the half below you is a giant factory city! You land near the gradually-filling pool of lava at the base of your new *lavafall*. Lavaducts will eventually carry the lava throughout the city, but to make use of it immediately, Elves are loading it into large [crucibles](https://en.wikipedia.org/wiki/Crucible) on wheels. The crucibles are top-heavy and pushed by hand. Unfortunately, the crucibles become very difficult to steer at high speeds, and so it can be hard to go in a straight line for very long. To get Desert Island the machine parts it needs as soon as possible, you'll need to find the best way to get the crucible *from the lava pool to the machine parts factory*. To do this, you need to minimize *heat loss* while choosing a route that doesn't require the crucible to go in a *straight line* for too long. Fortunately, the Elves here have a map (your puzzle input) that uses traffic patterns, ambient temperature, and hundreds of other parameters to calculate exactly how much heat loss can be expected for a crucible entering any particular city block. For example: ``` 2413432311323 3215453535623 3255245654254 3446585845452 4546657867536 1438598798454 4457876987766 3637877979653 4654967986887 4564679986453 1224686865563 2546548887735 4322674655533 ``` Each city block is marked by a single digit that represents the *amount of heat loss if the crucible enters that block*. The starting point, the lava pool, is the top-left city block; the destination, the machine parts factory, is the bottom-right city block. (Because you already start in the top-left block, you don't incur that block's heat loss unless you leave that block and then return to it.) Because it is difficult to keep the top-heavy crucible going in a straight line for very long, it can move *at most three blocks* in a single direction before it must turn 90 degrees left or right. The crucible also can't reverse direction; after entering each city block, it may only turn left, continue straight, or turn right. One way to *minimize heat loss* is this path: ``` 2>>34^>>>1323 32v>>>35v5623 32552456v>>54 3446585845v52 4546657867v>6 14385987984v4 44578769877v6 36378779796v> 465496798688v 456467998645v 12246868655 ``` This path never moves more than three consecutive blocks in the same direction and incurs a heat loss of only `*102*`. Directing the crucible from the lava pool to the machine parts factory, but not moving more than three consecutive blocks in the same direction, *what is the least heat loss it can incur?* Your puzzle answer was `855`. \--- Part Two --- ---------- The crucibles of lava simply aren't large enough to provide an adequate supply of lava to the machine parts factory. Instead, the Elves are going to upgrade to *ultra crucibles*. Ultra crucibles are even more difficult to steer than normal crucibles. Not only do they have trouble going in a straight line, but they also have trouble turning! Once an ultra crucible starts moving in a direction, it needs to move *a minimum of four blocks* in that direction before it can turn (or even before it can stop at the end). However, it will eventually start to get wobbly: an ultra crucible can move a maximum of *ten consecutive blocks* without turning. In the above example, an ultra crucible could follow this path to minimize heat loss: ``` 2>>>>>>>>1323 32154535v5623 32552456v4254 34465858v5452 45466578v>>>> 143859879845v 445787698776v 363787797965v 465496798688v 456467998645v 122468686556v 254654888773v 432267465553v ``` In the above example, an ultra crucible would incur the minimum possible heat loss of `*94*`. Here's another example: ``` 111111111111 999999999991 999999999991 999999999991 999999999991 ``` Sadly, an ultra crucible would need to take an unfortunate path like this one: ``` 1>>>>>>>1111 9999999v9991 9999999v9991 9999999v9991 9999999v>>>> ``` This route causes the ultra crucible to incur the minimum possible heat loss of `*71*`. Directing the *ultra crucible* from the lava pool to the machine parts factory, *what is the least heat loss it can incur?* Your puzzle answer was `980`. Both parts of this puzzle are complete! They provide two gold stars: \*\* At this point, you should [return to your Advent calendar](/2023) and try another puzzle. If you still want to see it, you can [get your puzzle input](17/input).