144 lines
3.7 KiB
C++
144 lines
3.7 KiB
C++
#include "AdventHelpers/AdventOfCodeSolution.h"
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#include <iostream>
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#include <cassert>
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#include <string>
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#include <cstring>
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#include <sstream>
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class Range {
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public:
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using range_t = long long;
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Range(range_t minValue, range_t maxValue)
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: mMinValue(minValue)
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, mMaxValue(maxValue)
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{
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}
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inline range_t left() const { return mMinValue; }
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inline range_t right() const { return mMaxValue; }
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private:
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const range_t mMinValue;
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const range_t mMaxValue;
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};
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class Day02Solution : public AdventHelpers::AdventOfCodeSolution
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{
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public:
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using RangeList = std::vector<Range>;
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static RangeList ParseLine(std::string line) {
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size_t index = 0;
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RangeList ranges;
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while (line.length() > 0) {
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std::string left, right;
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size_t start = 0;
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size_t leftEnd = line.substr(start).find('-');
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size_t rightEnd = line.substr(leftEnd).find(',');
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if (rightEnd == std::string::npos) rightEnd = line.length() - 1;
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left = line.substr(start, leftEnd);
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right = line.substr(leftEnd+1, rightEnd-1);
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ranges.push_back(Range(std::stoll(left), std::stoll(right)));
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line.erase(0, leftEnd + rightEnd + 1);
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}
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return ranges;
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}
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// An ID is invalid if the first half and the second half match.
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// It necessarily must be even.
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static bool isValidPart01(const std::string number) {
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if (number.length() % 2 == 0) {
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const size_t halfLength = number.length() / 2;
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std::string left = number.substr(0, halfLength);
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std::string right = number.substr(halfLength);
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if (left.compare(right) == 0) {
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return false;
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}
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}
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return true;
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}
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// In part 2, an id is invalid if it has some sequence repeated at least twice.
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// 111 = 1 three times, invalid
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// 121212 = 12 three times, invalid
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// 123123 = same as above, 123 twice
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static bool isValidPart02(const std::string number) {
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// Once we hit half the length, it must be the same on both sides
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const size_t halfLen = number.length() / 2;
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// Start from one character and work up
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for (int i = 0; i < halfLen; i++) {
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const auto substr = number.substr(0, i + 1);
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std::string temp(number);
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while (temp.substr(0, substr.length()).compare(substr) == 0) {
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temp.erase(0, substr.length());
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}
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if (temp.length() == 0) return false;
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}
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return true;
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}
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virtual std::string SolveProblem01(AdventHelpers::InputFileHelper& inputFile) override {
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std::string line = inputFile.getLine(0);
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auto ranges = ParseLine(line);
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Range::range_t sum = 0;
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for (const auto& range : ranges) {
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auto left = range.left();
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auto right = range.right();
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for (Range::range_t i = left; i <= right; i++) {
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if (!isValidPart01(std::to_string(i)))
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sum += i;
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}
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}
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return std::to_string(sum);
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}
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virtual std::string SolveProblem02(AdventHelpers::InputFileHelper& inputFile) override {
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std::string line = inputFile.getLine(0);
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auto ranges = ParseLine(line);
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Range::range_t sum = 0;
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for (const auto& range : ranges) {
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auto left = range.left();
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auto right = range.right();
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for (Range::range_t i = left; i <= right; i++) {
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if (!isValidPart02(std::to_string(i)))
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sum += i;
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}
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}
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return std::to_string(sum);
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}
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};
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int main(const char* argv[], int argc)
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{
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Day02Solution solution;
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solution.SolveAll();
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return 0;
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}
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