进制转换C答案，完美通过。

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define str_lenth 1000
/* run this program using the console pauser or add your own getch, system("pause") or input loop */

char str[str_lenth]={'0'};
int a;
char c;

    int func_lenth(char* str,int lenth)                                //测量字符串长度函数 
    {
        int i;

        for(i=0;i<lenth;i++)                                        
        {    
            if(str[i]=='\0')
            {
                lenth=i;
                break;
            }
        }

    return lenth;
    }

int num_change(char n)            //16进制字符转int 
{
    if((48<=n)&&(57>=n))return n-48;

    if(n=='A'||n=='a')return 10;
    if(n=='B'||n=='a')return 11;
    if(n=='C'||n=='a')return 12;    
    if(n=='D'||n=='a')return 13;        
    if(n=='E'||n=='a')return 14;    
    if(n=='F'||n=='a')return 15;

}

int change_16_to_10(char* str)
{
    int f=0,b=0,c=0,d=0,e=0;
    int sum=0;
    int bit=1;
    int i;

    bit=func_lenth(str,str_lenth)-2;

            f=num_change(str[2])*pow(16,(bit-1));
    if(bit>1)b=num_change(str[3])*pow(16,(bit-2));
    if(bit>2)c=num_change(str[4])*pow(16,(bit-3));
    if(bit>3)d=num_change(str[5])*pow(16,(bit-4));
    if(bit>4)e=num_change(str[6])*pow(16,(bit-5));




    sum=f+b+c+d+e;


    return sum;
} 



int main()
{


while(    scanf("%s",str)!=EOF) 
{
printf("%d\n",change_16_to_10(str));
} 
//while(1);
}