#include #include #include #include #include #define INPUTLEN 20000 static int* expand(size_t *lenp, const char *mp, size_t maplen) { size_t len = 0; for (size_t i = 0; i < maplen; i++) len += mp[i] - '0'; int *disk = malloc(len * sizeof(int)); size_t cursor = 0; for (size_t i = 0; i + 1 < maplen; i += 2) { for (int j = 0; j < mp[i] - '0'; j++) disk[cursor++] = i / 2; for (int j = 0; j < mp[i+1] - '0'; j++) disk[cursor++] = -1; } if (maplen % 2 == 1) { size_t i = maplen - 1; for (int j = 0; j < mp[i] - '0'; j++) disk[cursor++] = i / 2; } *lenp = len; return disk; } static size_t compact(int *disk, size_t len) { size_t j = len; // one past the last non-empty block while (j > 0 && disk[j-1] == -1) j--; for (size_t i = 0; i < j - 1; i++) { if (disk[i] != -1) continue; disk[i] = disk[--j]; while (j > 0 && disk[j-1] == -1) j--; } return j; } static size_t defragment(int *disk, size_t len) { // TODO } static size_t checksum(int *disk, size_t len) { size_t sum = 0; for (size_t i = 0; i < len && disk[i] != -1; i++) { sum += i * disk[i]; } return sum; } static void print_disk(int *disk, size_t len) { for (size_t i = 0; i < len; i++) { if (i != 0) putchar(' '); if (disk[i] == -1) putchar('.'); else printf("%d", disk[i]); } putchar('\n'); } int main(void) { char *diskmap = malloc(INPUTLEN + 1); size_t nr = fread(diskmap, 1, INPUTLEN, stdin); assert(nr <= INPUTLEN); while (nr > 0 && isspace(diskmap[nr-1])) nr--; diskmap[nr] = 0; size_t disklen; int *disk = expand(&disklen, diskmap, nr); int *disk2 = malloc(disklen * sizeof(int)); memcpy(disk2, disk, disklen * sizeof(int)); size_t disklen1 = compact(disk, disklen); printf("%zu\n", checksum(disk, disklen1)); size_t disklen2 = defragment(disk2, disklen); printf("%zu\n", checksum(disk2, disklen2)); }