180 lines
3.2 KiB
C++
180 lines
3.2 KiB
C++
#include <BAN/HashMap.h>
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#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 <string.h>
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int puzzle1(FILE* fp)
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{
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using BAN::Vector, BAN::String;
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Vector<String> lines;
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char buffer[256];
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while (fgets(buffer, sizeof(buffer), fp))
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{
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buffer[strlen(buffer) - 1] = '\0';
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MUST(lines.emplace_back(buffer));
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}
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int result = 0;
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for (size_t y = 0; y < lines.size(); y++)
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{
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for (size_t x = 0; x < lines[y].size(); x++)
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{
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if (!isdigit(lines[y][x]))
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continue;
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bool should_add = false;
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for (ssize_t y_off = -1; y_off <= 1; y_off++)
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{
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if ((ssize_t)y + y_off < 0)
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continue;
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if (y + y_off >= lines.size())
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break;
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for (ssize_t x_off = -1;; x_off++)
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{
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if ((ssize_t)x + x_off < 0)
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continue;
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if (x + x_off >= lines[y + y_off].size())
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break;
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if (x_off > 0 && !isdigit(lines[y][x + x_off - 1]))
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break;
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char c = lines[y + y_off][x + x_off];
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if (!isdigit(c) && c != '.')
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{
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should_add = true;
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break;
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}
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}
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if (should_add)
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break;
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}
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int number = 0;
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for (; x < lines[y].size(); x++)
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{
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if (!isdigit(lines[y][x]))
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{
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x--;
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break;
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}
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number = (number * 10) + (lines[y][x] - '0');
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}
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if (should_add)
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result += number;
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}
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}
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return result;
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}
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int puzzle2(FILE* fp)
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{
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using BAN::Vector, BAN::String, BAN::HashMap;
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Vector<String> lines;
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char buffer[256];
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while (fgets(buffer, sizeof(buffer), fp))
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{
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buffer[strlen(buffer) - 1] = '\0';
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MUST(lines.emplace_back(buffer));
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}
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// Didn't want to think about O(1) space, this is much simpler.
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// Map numbers next to '*' to asterisk's coordinates.
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HashMap<uint32_t, Vector<int>> gears;
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for (size_t y = 0; y < lines.size(); y++)
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{
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for (size_t x = 0; x < lines[y].size(); x++)
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{
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if (!isdigit(lines[y][x]))
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continue;
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int number = 0;
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for (int i = 0; x + i < lines[y].size(); i++)
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{
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if (!isdigit(lines[y][x + i]))
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break;
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number = (number * 10) + (lines[y][x + i] - '0');
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}
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for (ssize_t y_off = -1; y_off <= 1; y_off++)
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{
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if ((ssize_t)y + y_off < 0)
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continue;
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if (y + y_off >= lines.size())
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break;
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for (ssize_t x_off = -1;; x_off++)
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{
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if ((ssize_t)x + x_off < 0)
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continue;
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if (x + x_off >= lines[y + y_off].size())
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break;
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if (x_off > 0 && !isdigit(lines[y][x + x_off - 1]))
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break;
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if (lines[y + y_off][x + x_off] == '*')
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{
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uint32_t index = (y + y_off) << 16 | (x + x_off);
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if (!gears.contains(index))
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MUST(gears.insert(index, {}));
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MUST(gears[index].push_back(number));
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}
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}
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}
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for (; x < lines[y].size(); x++)
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{
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if (isdigit(lines[y][x]))
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continue;
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x--;
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break;
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}
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}
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}
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int result = 0;
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for (auto& [_, nums] : gears)
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{
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if (nums.size() != 2)
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continue;
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result += nums[0] * nums[1];
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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/day3_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: %d\n", puzzle1(fp));
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fseek(fp, 0, SEEK_SET);
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printf("puzzle2: %d\n", puzzle2(fp));
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fclose(fp);
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}
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