some_challenge.c

some_challenge.c

int main(void) {
    unsigned char *value = NULL;
    size_t size = 0;

    for (;;) {
        int c = getchar();
        if (c == EOF) {
            break;
        }

        size_t s = size + 1;
        s &= size;
        if (s == 0) {
            void *temp = realloc(value, size * 2 + 1);
            if (temp == NULL) {
                perror("realloc");
                exit(EXIT_FAILURE);
            }
            value = temp;
        }

        value[size++] = c;
    }

    puts(value);
    while (size-- > 0) {
        putchar(value[size]);
    }
    putchar('\n');
}