#include <bits/stdc++.h>using namespace std;int digit[20];long long dp[20][3];long long DFS(int pos, int have, int flag)//have 0 表示无 1 表示前一位为4 2 表示已经有49{if(pos == -1) return have == 2;if(!flag && dp[pos][have] != -1)return dp[pos][have];int end = flag ? digit[pos] : 9;long long ans = 0;//int nhave = have;for(int i=0; i<=end; i++){//int nhave = have;//if(have == 1 && i != 4)//nhave = 0;//if(have == 0 && i == 4)//nhave = 1;//if(have == 1 && i == 9)//nhave = 2;int nhave = have;//if(i == 4) nhave = 1;if(have == 1){if(i == 9) nhave = 2;else nhave = 0;}if(i == 4) nhave = 1;ans += DFS(pos-1, nhave, i == end && flag);}if(!flag)dp[pos][have] = ans;return ans;}long long Cal(int n){int pos = 0;while(n){digit[pos++] = n % 10;n /= 10;}return DFS(pos – 1, 0, 1);}int main(){freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);int n, T;cin>>T;while(T–){cin>>n;memset(dp, -1, sizeof(dp));cout<<Cal(n)<<endl;}return 0;}
，风景如何，其实并不重要。重要的是，你在我的身边。
