banan-os/userspace/aoc2023/day7/main.cpp

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#include <BAN/Vector.h>
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#include <BAN/Sort.h>
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#include <BAN/String.h>
#include <ctype.h>
#include <inttypes.h>
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#include <stdio.h>
#include <stdint.h>
using i64 = int64_t;
i64 parse_i64(BAN::StringView part)
{
i64 result = 0;
for (char c : part)
{
if (!isdigit(c))
break;
result = (result * 10) + (c - '0');
}
return result;
}
struct Hand
{
BAN::String hand;
i64 bid;
};
i64 card_score(char card, bool joker)
{
if (card == 'A')
return 14;
if (card == 'K')
return 13;
if (card == 'Q')
return 12;
if (card == 'J')
return joker ? 1 : 11;
if (card == 'T')
return 10;
ASSERT('2' <= card && card <= '9');
return card - '0';
}
i64 hand_score_no_type(const Hand& hand, bool joker)
{
ASSERT(hand.hand.size() == 5);
i64 score = 0;
for (char c : hand.hand)
score = (score << 4) | card_score(c, joker);
ASSERT(score < 1'000'000);
return score;
}
i64 hand_score(const Hand& hand, bool joker)
{
ASSERT(hand.hand.size() == 5);
i64 joker_count = 0;
i64 cnt[26 + 10] {};
for (char c : hand.hand)
{
if (isdigit(c))
cnt[c - '0' + 0]++;
else if (joker && c == 'J')
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joker_count++;
else
cnt[c - 'A' + 10]++;
}
i64 freq_max1 = 0;
i64 freq_max2 = 0;
for (size_t i = 0; i < 36; i++)
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{
if (cnt[i] > freq_max1)
{
freq_max2 = freq_max1;
freq_max1 = cnt[i];
}
else if (cnt[i] > freq_max2)
{
freq_max2 = cnt[i];
}
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}
freq_max1 += joker_count;
if (freq_max1 == 5)
return 6'000'000 + hand_score_no_type(hand, joker);
if (freq_max1 == 4)
return 5'000'000 + hand_score_no_type(hand, joker);
if (freq_max1 == 3 && freq_max2 == 2)
return 4'000'000 + hand_score_no_type(hand, joker);
if (freq_max1 == 3)
return 3'000'000 + hand_score_no_type(hand, joker);
if (freq_max1 == 2 && freq_max2 == 2)
return 2'000'000 + hand_score_no_type(hand, joker);
if (freq_max1 == 2)
return 1'000'000 + hand_score_no_type(hand, joker);
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return hand_score_no_type(hand, joker);
}
i64 puzzle(FILE* fp, bool joker)
{
BAN::Vector<Hand> hands;
char buffer[128];
while (fgets(buffer, sizeof(buffer), fp))
{
BAN::StringView line(buffer);
if (line.size() < 7)
continue;
MUST(hands.emplace_back(
line.substring(0, 5),
parse_i64(line.substring(6))
));
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}
BAN::sort::sort(hands.begin(), hands.end(),
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[joker] (const Hand& lhs, const Hand& rhs) {
return hand_score(lhs, joker) < hand_score(rhs, joker);
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}
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);
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i64 score = 0;
for (size_t i = 0; i < hands.size(); i++)
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score += (i + 1) * hands[i].bid;
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return score;
}
int main(int argc, char** argv)
{
const char* file_path = "/usr/share/aoc2023/day7_input.txt";
if (argc >= 2)
file_path = argv[1];
FILE* fp = fopen(file_path, "r");
if (fp == nullptr)
{
perror("fopen");
return 1;
}
printf("puzzle1: %" PRId64 "\n", puzzle(fp, false));
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fseek(fp, 0, SEEK_SET);
printf("puzzle2: %" PRId64 "\n", puzzle(fp, true));
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fclose(fp);
}