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--- Day 14: Space Stoichiometry ---
As you approach the rings of Saturn, your ship's [1m[97mlow fuel[0m indicator turns on. There isn't any fuel
here, but the rings have plenty of raw material. Perhaps your ship's Inter-Stellar Refinery Union
brand [1m[97mnanofactory[0m can turn these raw materials into fuel.
You ask the nanofactory to produce a list of the [1m[97mreactions[0m it can perform that are relevant to this
process (your puzzle input). Every reaction turns some quantities of specific [1m[97minput chemicals[0m into
some quantity of an [1m[97moutput chemical[0m. Almost every [1m[97mchemical[0m is produced by exactly one reaction; the
only exception, ORE, is the raw material input to the entire process and is not produced by a
reaction.
You just need to know how much [1m[97mORE[0m you'll need to collect before you can produce one unit of
[1m[97mFUEL[0m.
Each reaction gives specific quantities for its inputs and output; reactions cannot be partially
run, so only whole integer multiples of these quantities can be used. (It's okay to have leftover
chemicals when you're done, though.) For example, the reaction 1 A, 2 B, 3 C => 2 D means that
exactly 2 units of chemical D can be produced by consuming exactly 1 A, 2 B and 3 C. You can run
the full reaction as many times as necessary; for example, you could produce 10 D by consuming 5 A,
10 B, and 15 C.
Suppose your nanofactory produces the following list of reactions:
10 ORE => 10 A
1 ORE => 1 B
7 A, 1 B => 1 C
7 A, 1 C => 1 D
7 A, 1 D => 1 E
7 A, 1 E => 1 FUEL
The first two reactions use only ORE as inputs; they indicate that you can produce as much of
chemical A as you want (in increments of 10 units, each 10 costing 10 ORE) and as much of chemical B
as you want (each costing 1 ORE). To produce 1 FUEL, a total of [1m[97m31[0m ORE is required: 1 ORE to
produce 1 B, then 30 more ORE to produce the 7 + 7 + 7 + 7 = 28 A (with 2 extra A wasted) required
in the reactions to convert the B into C, C into D, D into E, and finally E into FUEL. (30 A is
produced because its reaction requires that it is created in increments of 10.)
Or, suppose you have the following list of reactions:
9 ORE => 2 A
8 ORE => 3 B
7 ORE => 5 C
3 A, 4 B => 1 AB
5 B, 7 C => 1 BC
4 C, 1 A => 1 CA
2 AB, 3 BC, 4 CA => 1 FUEL
The above list of reactions requires [1m[97m165[0m ORE to produce 1 FUEL:
- Consume 45 ORE to produce 10 A.
- Consume 64 ORE to produce 24 B.
- Consume 56 ORE to produce 40 C.
- Consume 6 A, 8 B to produce 2 AB.
- Consume 15 B, 21 C to produce 3 BC.
- Consume 16 C, 4 A to produce 4 CA.
- Consume 2 AB, 3 BC, 4 CA to produce 1 FUEL.
Here are some larger examples:
- [1m[97m13312[0m ORE for 1 FUEL:
157 ORE => 5 NZVS
165 ORE => 6 DCFZ
44 XJWVT, 5 KHKGT, 1 QDVJ, 29 NZVS, 9 GPVTF, 48 HKGWZ => 1 FUEL
12 HKGWZ, 1 GPVTF, 8 PSHF => 9 QDVJ
179 ORE => 7 PSHF
177 ORE => 5 HKGWZ
7 DCFZ, 7 PSHF => 2 XJWVT
165 ORE => 2 GPVTF
3 DCFZ, 7 NZVS, 5 HKGWZ, 10 PSHF => 8 KHKGT
- [1m[97m180697[0m ORE for 1 FUEL:
2 VPVL, 7 FWMGM, 2 CXFTF, 11 MNCFX => 1 STKFG
17 NVRVD, 3 JNWZP => 8 VPVL
53 STKFG, 6 MNCFX, 46 VJHF, 81 HVMC, 68 CXFTF, 25 GNMV => 1 FUEL
22 VJHF, 37 MNCFX => 5 FWMGM
139 ORE => 4 NVRVD
144 ORE => 7 JNWZP
5 MNCFX, 7 RFSQX, 2 FWMGM, 2 VPVL, 19 CXFTF => 3 HVMC
5 VJHF, 7 MNCFX, 9 VPVL, 37 CXFTF => 6 GNMV
145 ORE => 6 MNCFX
1 NVRVD => 8 CXFTF
1 VJHF, 6 MNCFX => 4 RFSQX
176 ORE => 6 VJHF
- [1m[97m2210736[0m ORE for 1 FUEL:
171 ORE => 8 CNZTR
7 ZLQW, 3 BMBT, 9 XCVML, 26 XMNCP, 1 WPTQ, 2 MZWV, 1 RJRHP => 4 PLWSL
114 ORE => 4 BHXH
14 VRPVC => 6 BMBT
6 BHXH, 18 KTJDG, 12 WPTQ, 7 PLWSL, 31 FHTLT, 37 ZDVW => 1 FUEL
6 WPTQ, 2 BMBT, 8 ZLQW, 18 KTJDG, 1 XMNCP, 6 MZWV, 1 RJRHP => 6 FHTLT
15 XDBXC, 2 LTCX, 1 VRPVC => 6 ZLQW
13 WPTQ, 10 LTCX, 3 RJRHP, 14 XMNCP, 2 MZWV, 1 ZLQW => 1 ZDVW
5 BMBT => 4 WPTQ
189 ORE => 9 KTJDG
1 MZWV, 17 XDBXC, 3 XCVML => 2 XMNCP
12 VRPVC, 27 CNZTR => 2 XDBXC
15 KTJDG, 12 BHXH => 5 XCVML
3 BHXH, 2 VRPVC => 7 MZWV
121 ORE => 7 VRPVC
7 XCVML => 6 RJRHP
5 BHXH, 4 VRPVC => 5 LTCX
Given the list of reactions in your puzzle input, [1m[97mwhat is the minimum amount of ORE required to
produce exactly 1 FUEL?[0m
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