中国(北方)大学生程序设计训练赛(第三周)(Interesting sequence-找规律)

The first member of the considered sequence is 1. To generate a member of the sequence from the previous member, double the previous one and apply “digit sort-ing” to the result. The first 15 members of the sequence are as follows: 1, 2, 4, 8, 16, 23, 46, 29, 58, 116, 223, 446, 289, 578, 1156, …

Write a program to determine the value of the n-th member of this sequence.

n (1<=n<=1e9)

打表发现有循环节

#include <iostream>
#include <cmath>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <string>
#include <vector>
#include <map>
#include <functional>
#include <cstdlib>
#include <queue>
#include <stack>
using namespace std;
#define For(i,n) for(int i=1;i<=n;i++)
#define Fork(i,k,n) for(int i=k;i<=n;i++)
#define Rep(i,n) for(int i=0;i<n;i++)
#define ForD(i,n) for(int i=n;i;i--)
#define ForkD(i,k,n) for(int i=n;i>=k;i--)
#define RepD(i,n) for(int i=n;i>=0;i--)
#define Forp(x) for(int p=Pre[x];p;p=Next[p])
#define Forpiter(x) for(int &p=iter[x];p;p=Next[p])
#define Lson (o<<1)
#define Rson ((o<<1)+1)
#define MEM(a) memset(a,0,sizeof(a));
#define MEMI(a) memset(a,127,sizeof(a));
#define MEMi(a) memset(a,128,sizeof(a));
#define INF (2139062143)
#define F (1000000007)
#define ALL(x) (x).begin(),(x).end()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define vi vector<int>
#define pi pair<int,int>
#define SI(a) ((a).size())
typedef long long ll;
typedef unsigned long long ull;
ll mul(ll a,ll b){return (a*b)%F;}
ll add(ll a,ll b){return (a+b)%F;}
ll sub(ll a,ll b){return (a-b+llabs(a-b)/F*F+F)%F;}
void upd(ll &a,ll b){a=(a%F+b%F)%F;}
int read()
{
int x=0,f=1; char ch=getchar();
while(!isdigit(ch)) {if (ch=='-') f=-1; ch=getchar();}
while(isdigit(ch)) { x=x*10+ch-'0'; ch=getchar();}
return x*f;
}
#define MAXN (1234567)
ll f[MAXN];
int main() {
// freopen("B.in","r",stdin);
int T=read();
f[1]=1;
Fork(i,2,100) {
f[i]=f[i-1]*2;
vi v;
while(f[i]) v.pb(f[i]%10),f[i]/=10;
sort(ALL(v));
Rep(j,SI(v)) f[i]=f[i]*10+v[j];
}
For(kc,T) {
ll a=read();
printf("Case #%d: ",kc);
if (a>25) {
a-=25;
a%=6;
a+=25;
}printf("%lld\n",f[a]);
}
return 0;
}