# var y=2021;

## --- Day 7: The Treachery of Whales ---

A giant whale has decided your submarine is its next meal, and it's much faster than you are. There's nowhere to run!

Suddenly, a swarm of crabs (each in its own tiny submarine - it's too deep for them otherwise) zooms in to rescue you! They seem to be preparing to blast a hole in the ocean floor; sensors indicate a massive underground cave system just beyond where they're aiming!

The crab submarines all need to be aligned before they'll have enough power to blast a large enough hole for your submarine to get through. However, it doesn't look like they'll be aligned before the whale catches you! Maybe you can help?

There's one major catch - crab submarines can only move horizontally.

You quickly make a list of the horizontal position of each crab (your puzzle input). Crab submarines have limited fuel, so you need to find a way to make all of their horizontal positions match while requiring them to spend as little fuel as possible.

For example, consider the following horizontal positions:

``16,1,2,0,4,2,7,1,2,14``

This means there's a crab with horizontal position `16`, a crab with horizontal position `1`, and so on.

Each change of 1 step in horizontal position of a single crab costs 1 fuel. You could choose any horizontal position to align them all on, but the one that costs the least fuel is horizontal position `2`:

• Move from `16` to `2`: `14` fuel
• Move from `1` to `2`: `1` fuel
• Move from `2` to `2`: `0` fuel
• Move from `0` to `2`: `2` fuel
• Move from `4` to `2`: `2` fuel
• Move from `2` to `2`: `0` fuel
• Move from `7` to `2`: `5` fuel
• Move from `1` to `2`: `1` fuel
• Move from `2` to `2`: `0` fuel
• Move from `14` to `2`: `12` fuel

This costs a total of `37` fuel. This is the cheapest possible outcome; more expensive outcomes include aligning at position `1` (`41` fuel), position `3` (`39` fuel), or position `10` (`71` fuel).

Determine the horizontal position that the crabs can align to using the least fuel possible. How much fuel must they spend to align to that position?

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