hdu 4734 F(x)(数位dp)

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<string>
#include<vector>
#include<stack>
#include<bitset>
#include<cstdlib>
#include<cmath>
#include<set>
#include<list>
#include<deque>
#include<map>
#include<queue>
#define ll long long int
using namespace std;
inline ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
inline ll lcm(ll a,ll b){return a/gcd(a,b)*b;}
int moth[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
int dir[2][2]={1,0 ,0,1};
int dirs[8][2]={1,0 ,0,1 ,-1,0 ,0,-1, -1,-1 ,-1,1 ,1,-1 ,1,1};
const int inf=0x3f3f3f3f;
int bits[10];
int dp[10][10007]; //len位 需要凑sum的权值和 
int fa;
int v[11]={1,2,4,8,16,32,64,128,256,512};
int dfs(int len,int sum,bool ismax){
    if(!len) return sum<=fa;
    if(sum>fa) return 0;
    if(!ismax&&dp[len][fa-sum]>=0) return dp[len][fa-sum];
    int up=ismax?bits[len]:9;
    int cnt=0;
    for(int i=0;i<=up;i++){
        cnt+=dfs(len-1,sum+i*v[len-1],ismax&&i==up);
    }
    if(!ismax) dp[len][fa-sum]=cnt;
    return cnt;
}
int solve(int x){
    int len=0;
    while(x){
        bits[++len]=x%10;
        x/=10;
    }
    return dfs(len,0,true);
}
void cal(int a){
    int now=1;
    while(a){
        fa+=now*(a%10);
        a/=10; now*=2;
    }
}
int main(){
    int t;
    scanf("%d",&t);
    int w=0;
    memset(dp,-1,sizeof(dp));
    while(t--){
        fa=0;    
        int a,b; 
        scanf("%d%d",&a,&b);
        cal(a);
        printf("Case #%d: %d\n",++w,solve(b));
    }
    return 0;
}