forked from Bananymous/banan-os
143 lines
2.9 KiB
C++
143 lines
2.9 KiB
C++
#include <BAN/Optional.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 <inttypes.h>
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#include <stdio.h>
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using i8 = int8_t;
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using i16 = int16_t;
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using i32 = int32_t;
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using i64 = int64_t;
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using u8 = uint8_t;
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using u16 = uint16_t;
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using u32 = uint32_t;
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using u64 = uint64_t;
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using Grid = BAN::Vector<BAN::String>;
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BAN::Optional<i64> calculate_score(const Grid& grid, i64 skip_val = 0)
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{
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// horizontal reflection
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for (size_t x = 1; x < grid.front().size(); x++)
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{
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const size_t reflection_len = BAN::Math::min(x, grid.front().size() - x);
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bool has_reflection = true;
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for (size_t y = 0; y < grid.size() && has_reflection; y++)
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for (size_t x_off = 0; x_off < reflection_len && has_reflection; x_off++)
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if (grid[y][x - x_off - 1] != grid[y][x + x_off])
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has_reflection = false;
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if (has_reflection && (i64)x != skip_val)
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return x;
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}
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// vertical reflection
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for (size_t y = 1; y < grid.size(); y++)
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{
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const size_t reflection_len = BAN::Math::min(y, grid.size() - y);
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bool has_reflection = true;
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for (size_t x = 0; x < grid.front().size() && has_reflection; x++)
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for (size_t y_off = 0; y_off < reflection_len && has_reflection; y_off++)
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if (grid[y - y_off - 1][x] != grid[y + y_off][x])
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has_reflection = false;
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if (has_reflection && (i64)y * 100 != skip_val)
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return y * 100;
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}
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return {};
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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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Grid grid;
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while (buffer[0] != '\n')
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{
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ASSERT(buffer[strlen(buffer) - 1] == '\n');
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buffer[strlen(buffer) - 1] = '\0';
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MUST(grid.emplace_back(buffer));
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if (fgets(buffer, sizeof(buffer), fp) == nullptr)
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break;
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}
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result += *calculate_score(grid);
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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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Grid grid;
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while (buffer[0] != '\n')
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{
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ASSERT(buffer[strlen(buffer) - 1] == '\n');
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buffer[strlen(buffer) - 1] = '\0';
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MUST(grid.emplace_back(buffer));
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if (fgets(buffer, sizeof(buffer), fp) == nullptr)
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break;
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}
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i64 original = *calculate_score(grid);
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for (size_t y = 0; y < grid.size(); y++)
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{
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for (size_t x = 0; x < grid.front().size(); x++)
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{
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grid[y][x] = (grid[y][x] == '.') ? '#' : '.';
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if (auto res = calculate_score(grid, original); res.has_value())
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{
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result += *res;
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goto grid_done;
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}
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grid[y][x] = (grid[y][x] == '.') ? '#' : '.';
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}
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}
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ASSERT_NOT_REACHED();
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grid_done:
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continue;
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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/day13_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("puzzle2: %" PRId64 "\n", puzzle2(fp));
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fclose(fp);
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}
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