读入输出优化

就是用getchar（）；

int read_In() {
    int a = 0;
    bool minus = false;
    char ch = getchar();
    while (!(ch == '-' || (ch >= '0' && ch <= '9'))) ch = getchar();
    if (ch == '-') {
        minus = true;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        a = a * 10 + (ch - '0');
        ch = getchar();
    }
    if (minus) a = -a;
    return a;
}
void printOut(int x) {
    char buffer[20];
    int length = 0;
    bool minus = x < 0;
    if (minus) x = -x;
    do {
        buffer[length++] = x % 10 + '0';
        x /= 10;
    } while (x);
    if (minus) buffer[length++] = '-';
    do {
        putchar(buffer[--length]);
    } while (length);
    putchar('\n');
}