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Rewrite as four-dimensional route finding The grid isn't just a 2D grid. The constraints make it 4D: * X * Y * Last direction * Number of steps in that direction By tracking all four dimensions, we can find the shortest route for _all_ combinations of the constraint. Previously, we were dropping routes that were currently longer but ended up shorter because they could take subsequent steps that other routes couldn't.
author IBBoard <dev@ibboard.co.uk>
date Sun, 22 Sep 2024 11:30:53 +0100
parents a1b748f2c416
children
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a1b748f2c416 Implement day 23 "longest route finding"
IBBoard <dev@ibboard.co.uk>
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1 --- Day 23: A Long Walk ---
a1b748f2c416 Implement day 23 "longest route finding"
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a1b748f2c416 Implement day 23 "longest route finding"
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3 You have a map made of blocked spaces (#), open spaces (.) and slopes (^, >, v, and <). You can't go back up slopes.
a1b748f2c416 Implement day 23 "longest route finding"
IBBoard <dev@ibboard.co.uk>
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a1b748f2c416 Implement day 23 "longest route finding"
IBBoard <dev@ibboard.co.uk>
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5 What is the LONGEST route from the start (open space in the top row) to the end (open space in the bottom row).