125 lines
2.2 KiB
C++
125 lines
2.2 KiB
C++
#include <BAN/StringView.h>
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#include <BAN/Vector.h>
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#include <ctype.h>
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#include <inttypes.h>
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#include <stdio.h>
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#include <stdint.h>
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using i64 = int64_t;
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i64 parse_i64_all_digits(BAN::StringView part)
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{
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i64 result = 0;
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for (char c : part)
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if (isdigit(c))
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result = (result * 10) + (c - '0');
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return result;
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}
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i64 puzzle1(FILE* fp)
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{
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BAN::Vector<i64> times, distances;
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{
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char buffer[128];
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fgets(buffer, sizeof(buffer), fp);
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BAN::StringView line(buffer);
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line = line.substring(10);
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line = line.substring(0, line.size() - 1);
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auto split = MUST(line.split(' '));
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for (auto part : split)
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MUST(times.push_back(parse_i64_all_digits(part)));
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}
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{
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char buffer[128];
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fgets(buffer, sizeof(buffer), fp);
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BAN::StringView line(buffer);
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line = line.substring(10);
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line = line.substring(0, line.size() - 1);
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auto split = MUST(line.split(' '));
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for (auto part : split)
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MUST(distances.push_back(parse_i64_all_digits(part)));
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}
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ASSERT(times.size() == distances.size());
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i64 result = 1;
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for (size_t i = 0; i < times.size(); i++)
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{
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i64 time = times[i];
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i64 distance = distances[i];
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i64 min = distance / time - 1;
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while ((time - min) * min <= distance)
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min++;
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i64 max = min;
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while ((time - max) * max > distance)
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max++;
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result *= max - min;
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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 time = 0;
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i64 distance = 0;
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{
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char buffer[128];
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fgets(buffer, sizeof(buffer), fp);
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BAN::StringView line(buffer);
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line = line.substring(10);
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time = parse_i64_all_digits(line);
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}
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{
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char buffer[128];
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fgets(buffer, sizeof(buffer), fp);
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BAN::StringView line(buffer);
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line = line.substring(10);
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distance = parse_i64_all_digits(line);
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}
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i64 min = distance / time - 1;
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while ((time - min) * min <= distance)
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min++;
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i64 max = min;
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while ((time - max) * max > distance)
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max++;
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return max - min;
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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/day6_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: %" PRId64 "\n", puzzle1(fp));
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fseek(fp, 0, SEEK_SET);
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printf("puzzle1: %" PRId64 "\n", puzzle2(fp));
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fclose(fp);
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}
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