88 lines
2.7 KiB
C++
88 lines
2.7 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 <vector>
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#include <string>
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#include <iostream>
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#include <fstream>
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#include "types.hpp"
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auto find_sum(usize index, std::vector<u64> xmas) {
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for (auto i = index - 25; i < index - 1; ++i) {
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for (auto j = i + 1; j < index; ++j) {
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if (xmas[i] + xmas[j] == xmas[index]) {
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return true;
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}
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}
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}
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return false;
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}
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auto main(i32 argc, char * argv[]) -> i32 {
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auto xmas = std::vector<u64>();
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auto line = std::string();
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auto file = std::ifstream("day9.input");
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while (getline(file, line)) {
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xmas.push_back(std::stoll(line));
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}
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auto invalid = u64(0);
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for (auto i = usize(25); i < xmas.size(); ++i) {
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if (!find_sum(i, xmas)) {
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std::cout << (invalid = xmas[i]) << std::endl;
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break;
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}
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}
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auto head_index = 0;
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auto tail_index = 1;
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auto sum = xmas[0] + xmas[1];
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while (sum != invalid) {
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if (sum < invalid) {
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sum += xmas[++tail_index];
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} else if (head_index + 1 < tail_index) {
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sum -= xmas[head_index];
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++head_index;
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} else {
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head_index = tail_index + 1;
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tail_index = head_index + 1;
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sum = xmas[head_index] + xmas[tail_index];
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}
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}
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auto min = xmas[tail_index];
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auto max = xmas[tail_index];
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for (auto i = head_index; i < tail_index; ++i) {
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if (xmas[i] < min) {
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min = xmas[i];
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} else if (xmas[i] > max) {
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max = xmas[i];
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}
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}
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std::cout << (min + max) << std::endl;
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return 0;
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}
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