【WikiOI】【P1743】【反转卡片】【题解】【平衡树or rope】

来源：互联网发布：腐尸之屋知乎编辑：程序博客网时间：2024/06/06 12:48

传送门：www.wikioi.com/problem/1743/

康复计划第二弹，本来想练练Treap|Splay的，看到这么水的题直接rope秒杀

Code：

//ID:zky#include<cstdio>#include<cctype>#include<ext/rope>#include<iostream>#include<algorithm>using namespace std;using namespace __gnu_cxx;const int maxn=300010;rope<int>s1,s2,tmp1,tmp2;int n;int a[maxn];int getint(){int res=0,ok=0;char ch;while(1){ch=getchar();if(isdigit(ch)){res*=10;res+=ch-'0';ok=1;}else if(ok)break;}return res;}void rev(int size){tmp1=s1.substr(0,size);tmp2=s2.substr(n-size,size);s1=tmp2+s1.substr(size,n-size);s2=s2.substr(0,n-size)+tmp1;}int main(){n=getint();for(int i=0;i<n;i++)a[i]=getint();for(int i=0;i<n;i++)s1.push_back(a[i]);for(int i=n-1;i>=0;i--)s2.push_back(a[i]);int ans=0;while(s1[0]!=1){rev(s1[0]);ans++;if(ans>100000){puts("-1");return 0;}}cout<<ans<<endl;return 0;}

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