【ZOJ4070】Function and Function（签到）

题意：求 k 层嵌套的 f(x)

0<=x,k<=1e9

思路：迭代不会很多次后函数里就会=0或者1，再看层数奇偶直接返回答案

 #include<cstdio>
 #include<cstring>
 #include<string>
 #include<cmath>
 #include<iostream>
 #include<algorithm>
 #include<map>
 #include<set>
 #include<queue>
 #include<vector>
 using namespace std;
 typedef long long ll;
 typedef unsigned int uint;
 typedef unsigned long long ull;
 typedef pair<int,int> PII;
 typedef vector<int> VI;
 #define fi first
 #define se second
 #define MP make_pair
 #define N      110000
 #define M      51
 #define MOD 1000000007
 #define eps 1e-8
 #define pi     acos(-1)
 #define oo     1010000000

 int a[]={,,,,,,,,,};

 int f(int n)
 {
     int s=;
     do{
         s+=a[n%];
         n/=;
     }while(n);
     return s;
 }

 int g(int n,int k)
 {
     while(k--)
     {
         n=f(n);
         if(n==) return k%;
         if(n==) return -k%;
     }
     return n;
 }

 int main()
 {
      int cas;
      scanf("%d",&cas);
      for(int v=;v<=cas;v++)
      {
         int n,k;
         scanf("%d%d",&n,&k);
         printf("%d\n",g(n,k));
     }
     return ;
 }