一开始理解错题意了,以为4949对答案的贡献为2,所以dfs里有个sum参数
#include <bits/stdc++.h>
#define ll long long
using namespace std;
int len,dig[20];
ll dp[20][20][20];
ll dfs(int pos,int prev,int sum,bool limit){
if(pos==0){
return sum!=0;
}
if(!limit&&dp[pos][prev][sum]!=-1) return dp[pos][prev][sum];
int i;
int up = limit?dig[pos]:9;
ll ans = 0;
for(i = 0;i <= up;i ++){
if(prev==4&&i==9) ans += dfs(pos-1,i,sum+1,limit&&i==up);
else ans += dfs(pos-1,i,sum,limit&&i==up);
}
if(!limit) dp[pos][prev][sum] = ans;
return ans;
}
ll solve(ll n){
len = 0;
while(n!=0){
dig[++len] = n%10;
n /= 10;
}
return dfs(len,0,0,1);
}
int main()
{
//freopen("a.txt","r",stdin);
memset(dp,-1,sizeof(dp));
int T;
cin>>T;
while(T --){
ll l,r;
l = 1;
cin>>r;
cout<<solve(r)-solve(l-1)<<endl;
}
return 0;
}