117 lines
1.9 KiB
C++
117 lines
1.9 KiB
C++
#include <ctype.h>
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#include <stdio.h>
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#include <string.h>
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#define MAX(a, b) ((a) < (b)) ? (b) : (a)
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int parse_int_and_advance(const char*& ptr)
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{
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int result = 0;
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while (isdigit(*ptr))
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result = (result * 10) + (*ptr++ - '0');
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return result;
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}
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int puzzle1(FILE* fp)
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{
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int result = 0;
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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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const char* ptr = buffer;
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if (strncmp("Game ", ptr, 5))
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continue;
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ptr += 5;
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int id = parse_int_and_advance(ptr);
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ptr += 2;
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bool valid = true;
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while (*ptr && valid)
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{
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int count = parse_int_and_advance(ptr);
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ptr++;
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if (strncmp(ptr, "red", 3) == 0)
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valid = (count <= 12);
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if (strncmp(ptr, "green", 5) == 0)
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valid = (count <= 13);
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if (strncmp(ptr, "blue", 4) == 0)
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valid = (count <= 14);
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while (*ptr && !isdigit(*ptr))
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ptr++;
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}
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if (valid)
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result += id;
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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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{ int result = 0;
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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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const char* ptr = buffer;
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if (strncmp("Game ", ptr, 5))
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continue;
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ptr += 5;
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parse_int_and_advance(ptr);
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ptr += 2;
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int needed_red = 0;
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int needed_green = 0;
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int needed_blue = 0;
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while (*ptr)
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{
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int count = parse_int_and_advance(ptr);
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ptr++;
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if (strncmp(ptr, "red", 3) == 0)
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needed_red = MAX(needed_red, count);
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if (strncmp(ptr, "green", 5) == 0)
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needed_green = MAX(needed_green, count);
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if (strncmp(ptr, "blue", 4) == 0)
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needed_blue = MAX(needed_blue, count);
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while (*ptr && !isdigit(*ptr))
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ptr++;
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}
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result += needed_red * needed_green * needed_blue;
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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/day2_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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