读入与输出优化

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

使用getchar()

int print(int a){
	if(a<0){
		putchar('-');
		a=-a;
	}
	if(a>=10)print(a/10);
	putchar(a%10+'0');
}