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#include "input.h"
#include <stddef.h>
#include <stdio.h>
#include <err.h>
#define INPUT "input/02.txt"
#define EXPECTED1 13221L
#define EXPECTED2 13131L
enum draw {
rock = 1,
paper = 2,
scissors = 3,
};
struct round_p1 {
enum draw opponent;
enum draw me;
};
int compute_round_score_p1(struct round_p1* round) {
int score = (int) round->me;
enum draw opponent = round->opponent;
enum draw me = round->me;
if((opponent == rock && me == paper) || (opponent == paper && me == scissors) || (opponent == scissors && me == rock))
score += 6; // win
else if(opponent == me)
score += 3; // draw
// loss is 0
return score;
}
void parse_round_p1(struct round_p1* round, char* round_str) {
switch(round_str[0]) {
case 'A':
round->opponent = rock;
break;
case 'B':
round->opponent = paper;
break;
case 'C':
round->opponent = scissors;
break;
default:
err(2, "unknown opponent choice %c", round_str[0]);
}
switch(round_str[2]) {
case 'X':
round->me = rock;
break;
case 'Y':
round->me = paper;
break;
case 'Z':
round->me = scissors;
break;
default:
err(2, "unknown me choice %c", round_str[2]);
}
}
void part1(struct input_str* input) {
// compute max calories
long score = 0;
struct round_p1 r;
for(size_t i = 0; i < input->line_count; i++) {
parse_round_p1(&r, input->lines[i]);
int round_score = compute_round_score_p1(&r);
score += round_score;
}
CHECK(score, EXPECTED1)
}
enum round_result {
loss = 0,
draw = 3,
win = 6,
};
struct round_p2 {
enum draw opponent;
enum round_result result;
};
int compute_round_score_p2(struct round_p2* round) {
enum draw opponent = round->opponent;
enum round_result result = round->result;
enum draw me;
switch(result) {
case loss:
if(opponent == rock)
me = scissors;
else
me = (enum draw) ((int) opponent - 1);
break;
case draw:
me = opponent;
break;
case win:
if(opponent == scissors)
me = rock;
else
me = (enum draw) ((int) opponent + 1);
break;
default:
err(2, "unknown result type");
}
return (int) me + (int) result;
}
void parse_round_p2(struct round_p2* round, char* round_str) {
switch(round_str[0]) {
case 'A':
round->opponent = rock;
break;
case 'B':
round->opponent = paper;
break;
case 'C':
round->opponent = scissors;
break;
default:
err(2, "unknown opponent choice %c", round_str[0]);
}
switch(round_str[2]) {
case 'X':
round->result = loss;
break;
case 'Y':
round->result = draw;
break;
case 'Z':
round->result = win;
break;
default:
err(2, "unknown expected result %c", round_str[2]);
}
}
void part2(struct input_str* input) {
// compute max calories
long score = 0;
struct round_p2 r;
for(size_t i = 0; i < input->line_count; i++) {
parse_round_p2(&r, input->lines[i]);
int round_score = compute_round_score_p2(&r);
score += round_score;
}
CHECK(score, EXPECTED2)
}
int main() {
// read input
struct input_str input;
input_str_read(&input, INPUT);
// do stuff
part1(&input);
part2(&input);
// cleanup & exit
input_str_free(&input);
return 0;
}
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