UVA 11922 Permutation Transformer(splay树)

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建树时节点加1，当需要旋转[a,b]的时候，其实分裂的是[a+1,b+1]的元素，所以增大一个节点，那么最后减一就可以了，如果序列的树很乱，那么用数组下标来建树。

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>using namespace std;struct Node{    Node* ch[2];    int v,s;    int flip;    int cmp(int x) const {        int d=x-ch[0]->s;        if(d==1) return -1;        return (d<=0?0:1);    }    void maintain(){        s=1+ch[0]->s+ch[1]->s;    }    void pushdown(){        if(flip){            flip=0;            swap(ch[0],ch[1]);            ch[0]->flip=!ch[0]->flip;            ch[1]->flip=!ch[1]->flip;        }    }};Node* null=new Node();void rotate(Node* &o,int d){    Node* k=o->ch[d^1];o->ch[d^1]=k->ch[d];k->ch[d]=o;    o->maintain();k->maintain();o=k;}void splay(Node* &o,int k){    o->pushdown();    int d=o->cmp(k);    if(d==1) k-=o->ch[0]->s+1;    if(d!=-1)    {        Node* p=o->ch[d];        p->pushdown();        int d2=p->cmp(k);        int k2=(d2==0?k:k-p->ch[0]->s-1);        if(d2!=-1)        {            splay(p->ch[d2],k2);            if(d==d2) rotate(o,d^1);else rotate(o->ch[d],d);        }        rotate(o,d^1);    }}void split(Node* o,int k,Node* &left,Node* &right){    splay(o,k);    left=o;    right=o->ch[1];    o->ch[1]=null;    left->maintain();}Node* merge(Node* left,Node* right){    splay(left,left->s);    left->ch[1]=right;    left->maintain();    return left;}void build(Node* &o,int l,int r){    if(l>r) {o=null;return ;}    int mid=(l+r)/2;    o=new Node();    o->v=mid;    build(o->ch[0],l,mid-1);    build(o->ch[1],mid+1,r);    o->maintain();}void print(Node* o){    if(o!=null)    {        o->pushdown();        print(o->ch[0]);        if(o->v>1) printf("%d\n",o->v-1);        print(o->ch[1]);    }}void debug(Node* o,int f){    if(o!=null)    {        o->pushdown();        debug(o->ch[0],o->v);        printf("%d %d %d\n",o->v,f,o->s);        debug(o->ch[1],o->v);    }}void remove(Node* o){    if(o->ch[0]!=NULL) remove(o->ch[0]);    if(o->ch[1]!=NULL) remove(o->ch[1]);    delete o;    o=NULL;}Node* root;int main(){    int n,m;    scanf("%d%d",&n,&m);    build(root,1,n+1);//建树时节点加一//    debug(root,-1);cout<<endl;    while(m--)    {        int a,b;        scanf("%d%d",&a,&b);        Node *left,*mid,*right,*o;        split(root,a,left,o);        split(o,b-a+1,mid,right);        mid->flip^=1;        root=merge(merge(left,right),mid);//        debug(root,-1);cout<<endl;    }    print(root);    return 0;}

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