149 lines
2.9 KiB
C++
149 lines
2.9 KiB
C++
#include <BAN/String.h>
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#include <BAN/Vector.h>
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#include <ctype.h>
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#include <stdio.h>
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#include <stdint.h>
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using i32 = int32_t;
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using i64 = int64_t;
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using u32 = uint32_t;
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using u64 = uint64_t;
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i64 parse_i64(BAN::StringView sv)
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{
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bool negative = (!sv.empty() && sv.front() == '-');
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if (negative)
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sv = sv.substring(1);
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i64 result = 0;
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for (char c : sv)
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{
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if (!isdigit(c))
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break;
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result = (result * 10) + (c - '0');
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}
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return negative ? -result : result;
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}
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i64 puzzle1(FILE* fp)
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{
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i64 result = 0;
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char buffer[128];
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while (fgets(buffer, sizeof(buffer), fp))
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{
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BAN::StringView line(buffer);
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auto value_strs = MUST(line.split(' '));
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if (value_strs.empty())
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continue;
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BAN::Vector<BAN::Vector<i64>> values;
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MUST(values.emplace_back(value_strs.size() + 1, 0));
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for (size_t i = 0; i < value_strs.size(); i++)
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values.back()[i] = parse_i64(value_strs[i]);
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bool all_zeroes = false;
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while (!all_zeroes)
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{
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size_t last = values.size();
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MUST(values.emplace_back(values.back().size() - 1, 0));
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all_zeroes = true;
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for (size_t i = 0; i < values.back().size() - 1; i++)
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{
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i64 lhs = values[last - 1][i + 0];
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i64 rhs = values[last - 1][i + 1];
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values[last][i] = rhs - lhs;
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if (values[last][i] != 0)
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all_zeroes = false;
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}
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}
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for (size_t i = values.size() - 1; i > 0; i--)
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{
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const size_t len = values[i].size();
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i64 lhs = values[i - 1][len - 1];
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i64 res = values[i][len - 1];
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values[i - 1][len - 0] = res + lhs;
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}
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result += values.front().back();
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}
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return result;
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}
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i64 puzzle2(FILE* fp)
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{
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i64 result = 0;
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char buffer[128];
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while (fgets(buffer, sizeof(buffer), fp))
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{
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BAN::StringView line(buffer);
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auto value_strs = MUST(line.split(' '));
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if (value_strs.empty())
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continue;
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BAN::Vector<BAN::Vector<i64>> values;
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MUST(values.emplace_back(value_strs.size() + 1, 0));
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for (size_t i = 0; i < value_strs.size(); i++)
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values.back()[i + 1] = parse_i64(value_strs[i]);
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bool all_zeroes = false;
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while (!all_zeroes)
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{
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size_t last = values.size();
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MUST(values.emplace_back(values.back().size() - 1, 0));
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all_zeroes = true;
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for (size_t i = 1; i < values.back().size(); i++)
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{
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i64 lhs = values[last - 1][i + 0];
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i64 rhs = values[last - 1][i + 1];
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values[last][i] = rhs - lhs;
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if (values[last][i] != 0)
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all_zeroes = false;
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}
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}
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for (size_t i = values.size() - 1; i > 0; i--)
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{
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i64 rhs = values[i - 1][1];
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i64 res = values[i][0];
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values[i - 1][0] = rhs - res;
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}
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result += values.front().front();
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}
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return result;
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}
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int main(int argc, char** argv)
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{
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const char* file_path = "/usr/share/aoc2023/day9_input.txt";
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if (argc >= 2)
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file_path = argv[1];
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FILE* fp = fopen(file_path, "r");
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if (fp == nullptr)
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{
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perror("fopen");
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return 1;
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}
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printf("puzzle1: %lld\n", puzzle1(fp));
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fseek(fp, 0, SEEK_SET);
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printf("puzzle2: %lld\n", puzzle2(fp));
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fclose(fp);
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}
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