读入优化

 1 int input()  
 2 {  
 3     int p = 0, sum = 0, MIN = INF;  
 4     char ch;  
 5     ch = getchar();  
 6     while(1)
 7     {
 8         if(ch == ‘-‘ || (ch >= ‘0‘ && ch <= ‘9‘))
 9             break;
10         ch = getchar();
11     }
12         
13     if(ch == ‘-‘)  
14     {  
15         p = 1;  
16         ch = getchar();  
17     }  
18     while(ch >= ‘0‘ && ch <= ‘9‘)  
19     {  
20         sum = sum * 10 + ch - ‘0‘;  
21         ch = getchar();  
22     }  
23     return p ? -sum : sum;  
24 }