ACdream 1083 完美树

http://acdreamoj.sinaapp.com/problem.php?id=1083

第一道   数位dp  感触很深；

#include<iostream>
#include<stdio.h>
#include<cstring>
#include<algorithm>
using namespace std;

int  arr[11],num[11][4];
bool vis[11][4];


int judge( int stu,int i)
{
    if( i == 3 ) return (stu|1);
    if( i == 8 ) return (stu|2);
    return stu;
}

int DFS( int pos,int stu ,bool full )
{
    int res = 0,i;
    if( pos == -1 )
    {
        if(stu == 1 || stu == 2) return 1;
        return 0;
    }
    if( !full && vis[pos][stu] ) return  num[pos][stu];
    int Max = full?arr[pos]:9;
    for( i = 0; i <= Max; i++ )
      res += DFS( pos-1,judge( stu,i ),full && ( i == arr[pos] ) );
    num[pos][stu] = res;
    vis[pos][stu] = true;
    return res;
}

int solve( int X )
{
    int k = 0;
    memset( vis,false,sizeof(vis) );
    memset( num,0,sizeof(num) );
    while( X )
    {
        arr[k++] = X%10;
        X /=10;
    }
    return DFS( k-1,0,true );
}
int main( )
{
    int T,L,R;
    scanf("%d",&T);
    while( T-- )
    {
        scanf("%d%d",&L,&R);
        printf("%d\n",solve(R) - solve(L-1) );
    }
    return 0;
}