快读快写

int read() {
    register int x = 0,f = 1;register char ch;
    ch = getchar();
    while(ch > '9' || ch < '0'){if(ch == '-') f = -f;ch = getchar();}
    while(ch <= '9' && ch >= '0'){x = x * 10 + ch - 48;ch = getchar();}
    return x * f;
}

void write(int x){
	if(x<0){putchar('-');x=-x;}//若x为负数，输出符号并取其绝对值
	if(x>9){write(x/10);putchar(x%10+'0');}//输出绝对值（采用递归的做法，减少代码量）
	else putchar(x+'0');
	return; 
}

n >= 1e8时，比scanf和printf快一倍左右

参考：浅谈快读快写，快读和快写