{}动态规划}记忆化dp

先搞个模板

 #include<stdio.h>
 #include<string.h>
 using namespace std;
 typedef long long ll;
 int a[];
 ll dp[][];
 ll dfs(int pos,bool six,bool limit)
 {
     if(pos==) return six?:;
     int state=six?:;
     if(!limit&&dp[pos][state]!=-) return dp[pos][state];
     int up=limit?a[pos]:;
     ll ans=;
     for(int i=;i<=up;++i)
     {
         ans+=dfs(pos-,six||i==,limit&&i==a[pos]);
     }
     if(!limit) dp[pos][state]=ans;
     return ans;
 }
 ll solve(ll x)
 {
     memset(dp, -, sizeof(dp));
     int pos=;
     while(x)
     {
         a[++pos]=x%;
         x/=;
     }
     return dfs(pos,,);
 }
 int main()
 {
     ll le,ri;
     scanf("%lld %lld",&le,&ri);
     printf("%lld\n",solve(ri)-solve(le-));
     return ;
 }