uva 11922 - Permutation Transformer

splay的题；

学习白书上和网上的代码敲的；

 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 #include <algorithm>
 using namespace std;
 int n,m;
 struct node
 {
     node *ch[];
     int s,v;
     int flip;
     node(int v):v(v)
     {
         ch[]=ch[]=NULL;
         s=;
         flip=;
     }
     void maintain()
     {
         s=;
         if(ch[]!=NULL)s+=ch[]->s;
         if(ch[]!=NULL)s+=ch[]->s;
     }
     void pushdown()
     {
         if(flip)
         {
             flip=;
             swap(ch[],ch[]);
             if(ch[]!=NULL)ch[]->flip=!ch[]->flip;
             if(ch[]!=NULL)ch[]->flip=!ch[]->flip;
         }
     }
     int cmp(int x)const
     {
         int t=(ch[]==NULL)?:ch[]->s;
         if(t>=x)return ;
         if(t+==x)return -;
         return ;
     }
 };
 void rotate(node* &root,int d)
 {
     node *k=root->ch[d^];
     root->ch[d^]=k->ch[d];
     k->ch[d]=root;
     root=k;
     root->ch[d]->maintain();
     root->maintain();
 }

 void build(node* &root,int l,int r)
 {
     int mid=(l+r)>>;
     root=new node(mid);
     if(l<mid)build(root->ch[],l,mid-);
     if(r>mid)build(root->ch[],mid+,r);
     root->maintain();
 }

 void splay(node* &root,int k)
 {
     root->pushdown();
     int d=root->cmp(k);
     if(d==)
     {
         if(root->ch[]!=NULL)
             k-=root->ch[]->s;
         k--;
     }
     if(d!=-)
     {
         node *p=root->ch[d];
         p->pushdown();
         int d2=p->cmp(k);
         int k2=k;
         if(d2==)
         {
             if(p->ch[]!=NULL)
                 k2-=p->ch[]->s;
             k2--;
         }
         if(d2!=-)
         {
             splay(p->ch[d2],k2);
             if(d==d2) rotate(root,d^);
             else rotate(root->ch[d],d);
         }
         rotate(root,d^);
     }
     return;
 }

 void split(node *root,int k,node* &left,node* &right)
 {
     splay(root,k);
     left=root;
     right=root->ch[];
     root->ch[]=NULL;
     left->maintain();//左边的要维护，右边不需要；
 }

 node *merge(node *left,node *right)
 {
     splay(left,left->s);//
     left->ch[]=right;
     left->maintain();
     return left;
 }

 void dfs(node *root)
 {
     root->pushdown();
     if(root->ch[])dfs(root->ch[]);
     if(root->v&&root->v!=n+)printf("%d\n",root->v);
     if(root->ch[])dfs(root->ch[]);
 }

 void del(node *root)
 {
     if(root->ch[])del(root->ch[]);
     if(root->ch[])del(root->ch[]);
     delete root;
 }

 node *root;
 int main()
 {
     int a,b;
     while(scanf("%d%d",&n,&m)!=EOF)
     {
         root=NULL;
         build(root,,n+);
         while(m--)
         {
             scanf("%d%d",&a,&b);
             node *right,*mid,*left,*tmp,*o;
             split(root,a,left,o);
             split(o,b-a+,mid,right);
             if(right->s>)
             {
                 split(right,right->s-,tmp,o);
                 mid->flip^=;
                 root=merge(left,merge(merge(tmp,mid),o));
             }
             else
             {
                 mid->flip^=;
                 root=merge(left,merge(mid,right));
             }
         }
         dfs(root);
         del(root);
     }
     return ;
 }