B. Tavas and SaDDas

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题目链接：http://codeforces.com/problemset/problem/535/B

47 Lucky数字问题

比赛时用的是打表的代码，居然过不了！真不知道为什么，先记录下吧，以后可能会知道为什么。

DFS代码：

#include<iostream>#include<sstream>#include<cstdio>#include<cmath>#include<cstring>#include<algorithm>#include<vector>#include<queue>#include<set>#include<map>#include<string>#define LL long long#define INF 0x7fffffff//freopen("E:\\in.txt","r",stdin);using namespace std;int ans,n;void dfs(int t,int k){    if(t>=n) return;    if(t<n) ans++;    if(k<1000000000) dfs(k*4+t,k*10);    if(k<1000000000) dfs(k*7+t,k*10);}int main(){    while(cin>>n){        ans=1;        dfs(4,10);dfs(7,10);        cout<<ans<<endl;    }    return 0;}

打表代码：

#include<iostream>#include<sstream>#include<cstdio>#include<cmath>#include<cstring>#include<algorithm>#include<vector>#include<queue>#include<set>#include<map>#include<string>#define LL long long#define INF 0x7fffffff//freopen("E:\\in.txt","r",stdin);using namespace std;int ans[20000],tot;void bfs(){    queue<int> Q;    Q.push(4);Q.push(7);    while(!Q.empty()){        int tp=Q.front();Q.pop();        //if(tp<=100000000) cout<<tp<<endl;        ans[tot++]=tp;        int k=0;        int p=tp;        while(p) k++,p/=10;        int kk=(int)pow(10,k);        if(kk*4+tp<=1000000000 && kk*4+tp>0 && kk*4+tp>tp) Q.push(kk*4+tp);        if(kk*7+tp<=1000000000 && kk*7+tp>0 && kk*7+tp>tp) Q.push(kk*7+tp);    }}int main(){    tot=0;    bfs();    sort(ans,ans+tot);    //for(int i=0;i<(int)ans.size();i++) cout<<ans[i]<<" ";    int N;    while(cin>>N){        for(int i=0;i<tot;i++)            if(ans[i]==N) {                cout<<(i+1)<<endl;                break;            }    }    return 0;}

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