读入优化

 

void read(int &x)
{
    x=0; char c=getchar();
    while(!isdigit(c))  c=getchar(); 
    while(isdigit(c)) { x=x*10+c-'0'; c=getchar();  }
}

 

void read(int &x)
{
    x=0; int f=1; char c=getchar();
    while(!isdigit(c)) { if(c=='-') f=-1; c=getchar(); } 
    while(isdigit(c)) { x=x*10+c-'0'; c=getchar();  }
    x*=f;
}