E - Round Numbers

 #include <iostream>
 #include <algorithm>
 #include <cstdio>
 #include <cstring>
 #include <string>

 using namespace std;
 const int maxn = *1e9+;
 int dp[][];
 int a[];

 //lead是否有前导0
 int dfs(int pos,int sta, int lead, bool limit){
     if(pos == -)
         return sta >= ;
     if(!limit && !lead && dp[pos][sta] != -)
         return dp[pos][sta];
     int up = limit?a[pos]:;
     int ans = ;
     for(int i = ;i <= up;i++){
         if(lead && i == )
             ans += dfs(pos-, sta, lead, limit && a[pos] == i);    //有前导0的就不统计在内
         else{
             ans += dfs(pos-, sta + (i == ?:-),lead && i == ,limit && a[pos] == i);
         }
     }
     //无限制，切无前导0
     if(!limit && !lead)
         dp[pos][sta] = ans;
     return ans;
 }

 int solve(int x){
     int pos = ;
     while(x){
         a[pos++] = x&;
         x >>= ;
     }
     //32当作0使用
     return dfs(pos-, , true, true);
 }

 int main(){
     memset(dp, -, sizeof(dp));
     int a, b;
     while(~scanf("%d%d", &a, &b)){
         int ans = solve(b) - solve(a-);
         printf("%d\n", ans);
     }
     return ;
 }