forked from Bananymous/banan-os
97 lines
1.6 KiB
C++
97 lines
1.6 KiB
C++
#include <BAN/HashMap.h>
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#include <BAN/Vector.h>
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#include <BAN/Sort.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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i64 part1(FILE* fp)
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{
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BAN::Vector<i64> lhs;
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BAN::Vector<i64> rhs;
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for (;;) {
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i64 l, r;
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if (fscanf(fp, "%" SCNd64 " %" SCNd64 "\n", &l, &r) != 2)
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break;
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MUST(lhs.push_back(l));
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MUST(rhs.push_back(r));
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}
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BAN::sort::sort(lhs.begin(), lhs.end());
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BAN::sort::sort(rhs.begin(), rhs.end());
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i64 result = 0;
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for (size_t i = 0; i < lhs.size(); i++)
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result += BAN::Math::abs(lhs[i] - rhs[i]);
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return result;
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}
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i64 part2(FILE* fp)
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{
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BAN::HashMap<i64, i64> lhs;
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BAN::HashMap<i64, i64> rhs;
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constexpr auto increment_count =
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[](auto& map, i64 key) {
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auto it = map.find(key);
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if (it == map.end())
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MUST(map.insert(key, 1));
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else
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it->value++;
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};
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for (;;) {
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i64 l, r;
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if (fscanf(fp, "%" SCNd64 " %" SCNd64 "\n", &l, &r) != 2)
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break;
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increment_count(lhs, l);
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increment_count(rhs, r);
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}
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i64 result = 0;
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for (auto [id, count] : lhs) {
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auto it = rhs.find(id);
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if (it == rhs.end())
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continue;
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result += id * count * it->value;
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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/aoc2024/day1_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("part1: %" PRId64 "\n", part1(fp));
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fseek(fp, 0, SEEK_SET);
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printf("part2: %" PRId64 "\n", part2(fp));
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fclose(fp);
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}
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