原来这就叫暴力

#include<cstdio>
#include<cstring>
char a[21];
int n;
int pd(int i)
{
    if(a[i]=='0')return 0;
    else if(a[i]=='1')return 1;
    else if(a[i]=='2')return 2;
    else if(a[i]=='3')return 3;
    else if(a[i]=='4')return 4;
    else if(a[i]=='5')return 5;
    else if(a[i]=='6')return 6;
    else if(a[i]=='7')return 7;
    else if(a[i]=='8')return 8;
    else if(a[i]=='9')return 9;
    else if(a[i]=='A')return 10;
    else if(a[i]=='B')return 11;
    else if(a[i]=='C')return 12;
    else if(a[i]=='D')return 13;
    else if(a[i]=='E')return 14;
    else if(a[i]=='F')return 15;
    
}
int main()
{
    int ans=0,t=1;scanf("%s %d",a+1,&n);
    for(int i=strlen(a+1);i>=1;i--)
    {
        ans+=pd(i)*t;t*=n;
    }
    printf("%d",ans);
}