有多少个0 (How many 0's? ,UVa 11038)

#include <iostream>
#include <string.h>
#include <string>
#include <fstream>
#include <algorithm>
#include <stdio.h>
#include <vector>
#include <queue>
#include <set>
#include <cmath>
using namespace std;
const double eps = 1e-8;
const int INF=0x7fffffff;
unsigned long long uINF = ~0LL;
#define MAXN 10000007
typedef long long LL;
LL a[11];
void init()
{
    LL dig=10;a[0]=1;
    for(int i=1;i<10;i++)
    {
        a[i]=a[i-1]*10+dig;
        dig*=10;
   //     cout<<a[i]<<endl;
    }
}
string Reverse(string str1)
{
    string str2="";
    for(int i=str1.length()-1;i>=0;i--)
    str2+=str1[i];
    return str2;
}
LL solve(LL x)
{
    LL ans=0,temp,dig=1,y=0;
    while(x>=10)
    {
        temp=x%10;
        x/=10;
        if(temp)ans+=dig*x;
        else ans+=dig*(x-1)+y+1;
        y+=temp*dig;
        dig*=10;
    }
    return ans;
}
int main()
{
    LL m,n;
    init();
    while(scanf("%lld%lld",&m,&n),m+n>=0)
    {
        //cout<<solve(m)<<' '<<solve(n)<<endl;
        LL ans=solve(n)-solve(m-1);
        if(m==0)ans++;
        printf("%lld
",ans);

    }

    return 0;
}