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#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define ABS(a) ((a) < 0 ? -(a) : (a))
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
#define COUNT(a) ((int)(sizeof(a) / sizeof 0 [a]))
#define FORLINE \
char *line = NULL; \
size_t len = 0; \
while (getline(&line, &len, fp) != EOF)
#define FREELINE \
if (line) \
free(line)
#define FORCH \
char ch = 0; \
while ((ch = fgetc(fp)) != EOF)
#define WHOLE \
fseek(fp, 0, SEEK_END); \
long fsize = ftell(fp); \
fseek(fp, 0, SEEK_SET); \
char *data = malloc(fsize + 1); \
fread(data, 1, fsize, fp); \
data[fsize] = 0;
static int part_one(FILE *fp)
{
int pos1, pos2;
fscanf(fp, "Player 1 starting position: %d\nPlayer 2 starting position: %d", &pos1, &pos2);
int score1 = 0, score2 = 0;
int player = 0;
int a = 1, b = 2, c = 3;
int aah = 0;
while (score1 < 1000 && score2 < 1000) {
aah += 3;
if (player == 0) {
pos1 += (a += 3) + (b += 3) + (c += 3);
if (pos1 > 10)
pos1 = pos1 % 10 + 1;
score1 += pos1;
player = 1;
} else if (player == 1) {
pos2 += (a += 3) + (b += 3) + (c += 3);
if (pos2 > 10)
pos2 = pos2 % 10 + 1;
score2 += pos2;
player = 0;
}
}
return MIN(score1, score2) * aah;
}
struct won {
long a, b;
};
static struct {
int exists;
struct won won;
} cache[10][10][21][21] = { 0 };
static struct won count(long player1, long player2, long score1, long score2)
{
if (cache[player1 - 1][player2 - 1][score1][score2].exists)
return cache[player1 - 1][player2 - 1][score1][score2].won;
struct won won = { 0 };
for (int a = 1; a <= 3; a++) {
for (int b = 1; b <= 3; b++) {
for (int c = 1; c <= 3; c++) {
int sum = a + b + c;
long player_switch = (player1 + sum - 1) % 10 + 1;
long score_switch = score1 + player_switch;
if (score_switch >= 21) {
won.a += 1;
} else {
// Switch
struct won aah =
count(player2, player_switch, score2, score_switch);
won.a += aah.b;
won.b += aah.a;
}
}
}
}
cache[player1 - 1][player2 - 1][score1][score2].exists = 1;
cache[player1 - 1][player2 - 1][score1][score2].won = won;
return won;
}
static long part_two(FILE *fp)
{
int player1, player2;
fscanf(fp, "Player 1 starting position: %d\nPlayer 2 starting position: %d", &player1,
&player2);
struct won won = count(player1, player2, 0, 0);
return MAX(won.a, won.b);
}
int main(int argc, char *argv[])
{
(void)argc;
(void)argv;
FILE *fp = fopen("input", "r");
if (!fp)
exit(EXIT_FAILURE);
clock_t tic = clock();
printf("%d\n", part_one(fp));
rewind(fp);
printf("%lu\n", part_two(fp));
clock_t toc = clock();
printf("TIME: %f seconds\n", (double)(toc - tic) / CLOCKS_PER_SEC);
fclose(fp);
return 0;
}
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