71 lines
2.4 KiB
C++
71 lines
2.4 KiB
C++
/*******************************************************************************
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*
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* Copyright (c) 2020 Gnarwhal
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*
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* -----------------------------------------------------------------------------
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files(the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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*******************************************************************************/
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#include <unordered_map>
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#include <string>
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#include <iostream>
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#include <fstream>
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#include "../misc/types.hpp"
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#include "../misc/print.hpp"
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struct Pair{ u64 num; usize last; };
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auto day15() -> void {
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auto last = usize(0);
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auto index = usize(0);
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auto sequence = std::unordered_map<u64, u64>();
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{
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auto line = std::string();
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auto file = std::ifstream("inputs/day15.input");
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getline(file, line);
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auto start = usize(0);
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auto end = usize(0);
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auto num = std::string();
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while ((end = line.find(',', start)) != std::string::npos) {
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num = line.substr(start, end - start);
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sequence.insert_or_assign(u64(std::stoll(num)), ++index);
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start = end + 1;
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}
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end = line.size();
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num = line.substr(start, end - start);
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sequence.insert_or_assign(u64(std::stoll(num)), ++index);
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}
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while (++index < 30000000) {
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if (index == 2020) {
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print(last);
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}
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if (sequence.contains(last)) {
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auto new_last = index - sequence[last];
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sequence[last] = index;
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last = new_last;
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} else {
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sequence.insert_or_assign(last, index);
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last = 0;
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}
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}
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print(last);
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}
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