[转]数据输入加速

　　转自：http://blog.csdn.net/shahdza/article/details/6317011

①

//适用于正整数  
template <class T>  
inline void scan_d(T &ret) {  
    char c; ret=0;  
    while((c=getchar())<'0'||c>'9');  
    while(c>='0'&&c<='9') ret=ret*10+(c-'0'),c=getchar();  
}

②

//适用于正负整数  
template <class T>  
inline bool scan_d(T &ret) {  
   char c; int sgn;  
   if(c=getchar(),c==EOF) return 0; //EOF  
   while(c!='-'&&(c<'0'||c>'9')) c=getchar();  
   sgn=(c=='-')?-1:1;  
   ret=(c=='-')?0:(c-'0');  
   while(c=getchar(),c>='0'&&c<='9') ret=ret*10+(c-'0');  
   ret*=sgn;  
   return 1;  
}

 ③

//适用于正负数,(int,long long,float,double)  
template <class T>  
bool scan_d(T &ret){  
    char c; int sgn; T bit=0.1;  
    if(c=getchar(),c==EOF) return 0;  
    while(c!='-'&&c!='.'&&(c<'0'||c>'9')) c=getchar();  
    sgn=(c=='-')?-1:1;  
    ret=(c=='-')?0:(c-'0');  
    while(c=getchar(),c>='0'&&c<='9') ret=ret*10+(c-'0');  
    if(c==' '||c=='
'){ ret*=sgn; return 1; }  
    while(c=getchar(),c>='0'&&c<='9') ret+=(c-'0')*bit,bit/=10;  
    ret*=sgn;  
    return 1;  
}

inline void out(int x) {  
   if(x>9) out(x/10);  
   putchar(x%10+'0');  
}

  调用 scan_d(n) 对输入数据比较多的题目，有非常明显的加速效果！！！