The 2011 Rocky Mountain Regional Contest&&Iterated Difference

水题~~~

#include<iostream>#include<string.h>#include<stdio.h>#include<cmath>#include<algorithm>using namespace std;int s[21];int n;bool judge(){  for(int i=0;i<n-1;++i)if(s[i]!=s[i+1]) return false;return true;   }void Change(){for(int i=0;i<n;++i)s[i]=abs(s[i]-s[i+1]);    s[n]=s[0];}int main(){    int T=0;while(scanf("%d",&n)!=EOF,n){  T++;  for(int i=0;i<n;++i)scanf("%d",&s[i]);  s[n]=s[0];  int ans=0;  bool flag(false);   while(ans<=1000&&!flag)   {   Change();       if(!judge()) ans++;   else flag=true;   }   if(flag)  printf("Case %d: %d iterations\n",T,ans);   else      printf("Case %d: not attained\n",T);}return 0;}