HDU 4734 F(x)

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 int dp[10][200010],pos[10];
 4 int F(int x) {
 5     int b = 1,ret = 0;
 6     while(x) {
 7         ret += x%10*b;
 8         x /= 10;
 9         b <<= 1;
10     }
11     return ret;
12 }
13 int dfs(int len,int now,bool flag) {
14     if(len < 0) return now >= 0;
15     if(now < 0) return 0;
16     if(!flag && dp[len][now] != -1) return dp[len][now];
17     int d = flag?pos[len]:9,ret = 0;
18     for(int i = 0; i <= d; ++i)
19         ret += dfs(len-1,now-i*(1<<len),flag&&i==d);
20     if(!flag) dp[len][now] = ret;
21     return ret;
22 }
23 int calc(int a,int b) {
24     int cnt = 0;
25     while(b) {
26         pos[cnt++] = b%10;
27         b /= 10;
28     }
29     return dfs(cnt-1,F(a),true);
30 }
31 int main() {
32     int kase,a,b;
33     scanf("%d",&kase);
34     memset(dp,-1,sizeof dp);
35     for(int cs = 1; cs <= kase; ++cs) {
36         scanf("%d%d",&a,&b);
37         printf("Case #%d: %d\n",cs,calc(a,b));
38     }
39     return 0;
40 }