68 lines
1.5 KiB
C
68 lines
1.5 KiB
C
#include <stdio.h>
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#include <stdint.h>
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#include "puzzle_input.h"
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#include "day.h"
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#define STATES_MAX_LEN 500
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#define FISH_DAYS 9
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uint8_t states_g[STATES_MAX_LEN];
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typedef struct {
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uint64_t spawn_count[FISH_DAYS];
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uint8_t day_ndx;
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} fish_buffer_t;
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void insert_fish_at_ndx(fish_buffer_t * buff, uint8_t day_ndx, uint64_t count) {
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uint8_t norm_ndx = (buff->day_ndx + day_ndx) % FISH_DAYS;
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buff->spawn_count[norm_ndx] += count;
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}
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uint64_t fish_today(fish_buffer_t * buff) {
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return buff->spawn_count[buff->day_ndx];
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}
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void inc_day(fish_buffer_t * buff) {
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buff->day_ndx = (buff->day_ndx + 1) % FISH_DAYS;
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}
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int day_6() {
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parse_ret_t res;
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uint16_t len;
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uint16_t day = 0;
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uint64_t fish_count;
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fish_buffer_t fish_buffer = {0};
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res = read_input_split_on("../inputs/day_6.txt", (void *)states_g, 500, parse_byte_from_buff, &len, ',');
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if (res != PARSER_OK) {
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printf("Unable to parse input data: %d", res);
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return -1;
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}
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for (int initial_ndx = 0; initial_ndx < len; initial_ndx++) {
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fish_buffer.spawn_count[states_g[initial_ndx]]++;
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}
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fish_count = len;
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while (day < 256) {
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uint64_t spawns_today = fish_today(&fish_buffer);
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inc_day(&fish_buffer);
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insert_fish_at_ndx(&fish_buffer, 6, spawns_today);
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fish_count += spawns_today;
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day++;
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if (day == 80) {
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printf("PART 1: Fish count: %lu\n", fish_count);
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}
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}
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printf("PART 2: Fish count: %lu\n", fish_count);
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return 0;
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}
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