BZOJ 1251 序列终结者 Splay

题目大意：维护区间的最大值，要求可以区间翻转和区间加减。

思路：弱化版的1500，好长时间没写带标记的Splay了，错误重重。这个题可以当作带标记的Splay模板了。

CODE：

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#define INF 0x3f3f3f3f#define WORKPATH (root->son[1]->son[0])using namespace std;struct SplayTree{int val,size;int change,_max;bool reverse;SplayTree *son[2],*father;SplayTree(int _);bool Check() {return father->son[1] == this;}void Combine(SplayTree *a,bool dir) {son[dir] = a;a->father = this;}void Plus(int c);void Reverse();void PushUp();void PushDown();}none(0),*nil = &none,*root;SplayTree:: SplayTree(int _) {val = _;size = 1;_max = change = 0;reverse = false;son[0] = son[1] = nil;}void SplayTree:: Plus(int c) {if(this == nil)return ;change += c;val += c;_max += c;}void SplayTree:: Reverse() {if(this == nil)return ;reverse ^= 1;swap(son[0],son[1]);}void SplayTree:: PushUp() {if(this == nil)return ;size = son[0]->size + son[1]->size + 1;_max = max(val,max(son[0]->_max,son[1]->_max));}void SplayTree:: PushDown() {if(this == nil)return ;if(change) {son[0]->Plus(change);son[1]->Plus(change);change = 0;}if(reverse) {son[0]->Reverse();son[1]->Reverse();reverse = false;}}int cnt,asks;SplayTree *BuildTree(int l,int r){if(r < l)return nil;int mid = (l + r) >> 1;SplayTree *re = new SplayTree(0);re->Combine(BuildTree(l,mid - 1),false);re->Combine(BuildTree(mid + 1,r),true);re->PushUp();return re;}void Pretreatment(){nil->size = 0;nil->father = nil;nil->val = nil->_max = -INF;root = BuildTree(0,cnt + 1);root->father = nil;}inline void Rotate(SplayTree *a,bool dir){SplayTree *f = a->father;f->PushDown(),a->PushDown();f->son[!dir] = a->son[dir];f->son[!dir]->father = f;a->son[dir] = f;f->father->son[f->Check()] = a;a->father = f->father;f->father = a;f->PushUp();if(root == f)root = a;}inline void Splay(SplayTree *a,SplayTree *aim){while(a->father != aim) {if(a->father->father == aim)Rotate(a,!a->Check());else if(!a->father->Check()) {if(!a->Check())Rotate(a->father,true),Rotate(a,true);elseRotate(a,false),Rotate(a,true);}else {if(a->Check())Rotate(a->father,false),Rotate(a,false);elseRotate(a,true),Rotate(a,false);}}a->PushUp();}SplayTree *Kth(SplayTree *a,int k){a->PushDown();if(k <= a->son[0]->size)return Kth(a->son[0],k);k -= a->son[0]->size;if(k == 1)return a;return Kth(a->son[1],k - 1);}inline void SplaySeg(int x,int y){x++,y++;Splay(Kth(root,x - 1),nil);Splay(Kth(root,y + 1),root);}int main(){cin >> cnt >> asks;Pretreatment();for(int flag,x,y,z,i = 1; i <= asks; ++i) {scanf("%d",&flag);if(flag == 1) {scanf("%d%d%d",&x,&y,&z);SplaySeg(x,y);WORKPATH->Plus(z);root->son[1]->PushUp();root->PushUp();}else if(flag == 2) {scanf("%d%d",&x,&y);SplaySeg(x,y);WORKPATH->Reverse();}else {scanf("%d%d",&x,&y);SplaySeg(x,y);printf("%d\n",WORKPATH->_max);}}return 0;}