104 lines
2.1 KiB
C++
104 lines
2.1 KiB
C++
#include "aoc.hpp"
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#include <algorithm>
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class Day03 : public AOCDay
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{
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public:
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Day03() {}
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~Day03() {}
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int Day() override {return 3;}
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uint64_t PartOne(File& f) override
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{
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uint64_t totalJoltage = 0;
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for (auto bank : f.Lines())
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{
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int joltage = 0;
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// find biggest (can't be last)
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int biggest = 0;
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int biggestIndex = 0;
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for (int i = 0; i < bank.length() - 1; i++)
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{
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if (bank[i] - '0' > biggest)
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{
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biggest = bank[i] - '0';
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biggestIndex = i + 1;
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}
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}
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joltage = biggest;
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joltage *= 10;
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biggest = 0;
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for (int i = biggestIndex; i < bank.length(); i++)
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{
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if (bank[i] - '0' > biggest)
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{
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biggest = bank[i] - '0';
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}
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}
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joltage += biggest;
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totalJoltage += joltage;
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}
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return totalJoltage;
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}
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std::pair<int,int> FindNextBiggest(const std::string& s, int start, int k)
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{
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int remaining = 12 - k - 1;
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int lastAllowed = s.size() - remaining; // inclusive upper bound
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int bestDigit = -1;
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int bestIndex = start;
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for (int i = start; i < lastAllowed; i++)
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{
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int d = s[i] - '0';
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if (d > bestDigit)
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{
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bestDigit = d;
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bestIndex = i;
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}
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}
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return { bestDigit, bestIndex + 1 };
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}
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uint64_t PartTwo(File& f) override
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{
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uint64_t totalJoltage = 0;
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for (auto bank : f.Lines())
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{
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uint64_t joltage = 0;
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int start = 0;
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for (int k = 0; k < 12; k++)
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{
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joltage *= 10;
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auto res = FindNextBiggest(bank, start, k);
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joltage += res.first;
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start = res.second;
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}
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totalJoltage += joltage;
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}
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return totalJoltage;
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}
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};
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ADD_AOC_DAY(Day03);
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