HYSBZ 1500 [NOI2005]维修数列 splay

解题思路：终于把这道splay神题A掉了，splay专题也算是告一段落了，这个题主要的坑点，还是旋转和区间合并结合，网上神牛题解太多了，我就不写细节了

解题代码：

// File Name: hysbz1500.cpp
// Author: darkdream
// Created Time: 2015年04月10日 星期五 10时41分03秒

#include<vector>
#include<list>
#include<map>
#include<set>
#include<deque>
#include<stack>
#include<bitset>
#include<algorithm>
#include<functional>
#include<numeric>
#include<utility>
#include<sstream>
#include<iostream>
#include<iomanip>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<ctime>
#include<climits>
#define LL int
#define INF INT_MAX
#define maxn 500005
using namespace std;

struct SplayTree{
   int sz[maxn];
   int ch[maxn][2];
   int pre[maxn];
   int root , top1,top2;
   int ss[maxn],que[maxn];
   
   void Rotate(int x, int f){
        int y = pre[x];
        push_down(y);
        push_down(x);
        ch[y][!f] = ch[x][f];
        pre[ch[x][f]] = y ; 
        pre[x] = pre[y];
        if(pre[x]) ch[pre[y]][ch[pre[y]][1] == y] = x; 
        ch[x][f] = y;
        pre[y] = x; 
        push_up(y);
   }
   void Splay(int x, int goal){
        push_down(x);
        while(pre[x] != goal){
            if(pre[pre[x]] == goal){
                Rotate(x,ch[pre[x]][0] == x);
            }else {
                int y = pre[x],z = pre[y];
                int f = (ch[z][0] == y);
                if(ch[y][f] == x){
                    Rotate(x,!f),Rotate(x,f);
                }else{
                    Rotate(y,f),Rotate(x,f);
                }
            }
        }
        push_up(x);
        if(goal == 0) root = x; 
   }
   void RotateTo(int k ,int goal){
       int x = root;
       push_down(x);
       while(sz[ch[x][0]] != k ){
            if(k < sz[ch[x][0]]){
                x = ch[x][0];
            }else {
                k -= (sz[ch[x][0]] + 1);
                x = ch[x][1];
            }
            push_down(x);
       }
       Splay(x,goal);
   }
   void erase(int x){
        int father = pre[x];
        int head = 0 , tail = 0 ; 
        for(que[tail ++] = x; head < tail ;head ++){
            ss[top2 ++] = que[head];
            if(ch[ que[head]][0]) que[tail ++] = ch[que[head]][0];
            if(ch[ que[head]][1]) que[tail ++] = ch[que[head]][1];
        }
        ch[father][ch[father][1] ==  x] = 0 ; 
        push_up(father);
   }
   void update_same(int x, int c)
   {
       if(x == 0 ) return ;
       cg[x] = c; 
       val[x] = c; 
       sum[x] = sz[x] * c; 
       lx[x] = rx[x] = mx[x] = max(c,c*sz[x]);
   }
   void  update_rev(int x)
   {
       if(x == 0 )
           return; 
      rev[x] ^= 1; 
      swap(lx[x],rx[x]);
   }
   void push_down(int x)
   {
       if(cg[x] != -INF)
       {
           update_same(ch[x][1],cg[x]);
           update_same(ch[x][0],cg[x]);
           rev[x] = 0 ; 
           cg[x] = -INF; 
       }else if(rev[x] == 1)
       {
            swap(ch[x][0],ch[x][1]);
            update_rev(ch[x][0]);
            update_rev(ch[x][1]);
            rev[x] =  0 ; 
       }
   }
   void push_up(int x){
        sz[x] = 1 + sz[ch[x][0]] + sz[ch[x][1]];
        sum[x] =  val[x] + sum[ch[x][0]] + sum[ch[x][1]] ; 
        lx[x] = rx[x] = sum[x];
        mx[x] = sum[x];
        if(ch[x][0] == 0  && ch[x][1] == 0 ){
           return; 
        }
        if(ch[x][0] == 0 ){
            lx[x] = max(val[x],lx[x]);
            lx[x] = max(val[x]+lx[ch[x][1]],lx[x]);
            rx[x] = max(rx[ch[x][1]],rx[x]);
            mx[x] = max(mx[ch[x][1]],mx[x]);
            mx[x] = max(lx[x],mx[x]);
            mx[x] = max(rx[x],mx[x]);
        }else if(ch[x][1] == 0 ){
            lx[x] = max(lx[ch[x][0]],lx[x]);
            rx[x] = max(val[x],rx[x]);
            rx[x] = max(val[x] + rx[ch[x][0]],rx[x]);
            mx[x] = max(mx[ch[x][0]],mx[x]);
            mx[x] = max(lx[x],mx[x]);
            mx[x] = max(rx[x],mx[x]);
        }else{
            lx[x] = max(lx[ch[x][0]],lx[x]);
            lx[x] = max(sum[ch[x][0]] + val[x],lx[x]);
            lx[x] = max(sum[ch[x][0]] + val[x] + lx[ch[x][1]],lx[x]);        
            rx[x] = max(rx[ch[x][1]],rx[x]);
            rx[x] = max(sum[ch[x][1]] + val[x],rx[x]);
            rx[x] = max(sum[ch[x][1]] + val[x] + rx[ch[x][0]],rx[x]);
            mx[x] = max(val[x],mx[x]);
            mx[x] = max(mx[ch[x][0]],mx[x]);
            mx[x] = max(mx[ch[x][1]],mx[x]);
            mx[x] = max(rx[ch[x][0]]+val[x],mx[x]);
            mx[x] = max(sum[ch[x][0]]+val[x],mx[x]);
            mx[x] = max(lx[ch[x][1]]+val[x],mx[x]);
            mx[x] = max(sum[ch[x][1]]+val[x],mx[x]);
            mx[x] = max(lx[ch[x][1]]  + rx[ch[x][0]] + val[x],mx[x]);
        }
   }
   void NewNode(int &x , LL c){
        if(top2) x = ss[--top2];
        else x = ++ top1;
        rev[x] = ch[x][0] = ch[x][1] = pre[x] = 0 ;
        sz[x] = 1; 
        cg[x] = -INF;  
        val[x] = sum[x] = lx[x] = rx[x] = mx[x] = c ; 
   }
   void build(int &x,int l ,int r ,int f){
        if(l >  r) return ; 
        int m = (l + r) >> 1; 
        NewNode(x,num[m]);
        build(ch[x][0],l,m-1,x);
        build(ch[x][1],m+1,r,x);
        pre[x] = f; 
        push_up(x);
   }
   void init(){
      rev[0] = ch[0][0] = ch[0][1] = pre[0] = sz[0] = 0 ; 
      lx[0] = rx[0] = mx[0] = sum[0] = 0;
      cg[0] = -INF;
      root = top1 = 0 ; 
      NewNode(root,-1);
      NewNode(ch[root][1],-1);
      pre[ch[root][1]] = root;
      sz[root] = 2; 
      push_up(root);
   }
   void insert(int p ,int n){
       for(int i =1 ;i <= n;i ++)
            scanf("%d",&num[i]);
       RotateTo(p,0);
       RotateTo(p+1,root);
       build(ch[ch[root][1]][0],1,n,ch[root][1]);
       push_up(ch[root][1]);
       push_up(root);
   }
   void Del(int p , int n){
        RotateTo(p-1,0);
        RotateTo(p+n,root);
        erase(ch[ch[root][1]][0]);
        push_up(ch[root][1]);
        push_up(root);
   }
   void make(int p , int n, LL c){
        RotateTo(p-1,0);
        RotateTo(p+n,root);
        update_same(ch[ch[root][1]][0],c);
        push_up(ch[root][1]);
        push_up(root);
   }
   void flip(int p ,int n ){
       RotateTo(p-1,0);
       RotateTo(p+n,root);
       update_rev(ch[ch[root][1]][0]);
   }
   LL getsum(int p ,int n){
        RotateTo(p-1,0);
        RotateTo(p+n,root);
        printf("%d
",sum[ch[ch[root][1]][0]]);
   }
   LL maxsum(){
        RotateTo(0,0);
        RotateTo(sz[root]-1,root);
        LL tmx = -INF;
        tmx = max(lx[ch[ch[root][1]][0]],tmx);
        tmx = max(rx[ch[ch[root][1]][0]],tmx);
        tmx = max(mx[ch[ch[root][1]][0]],tmx);
        printf("%d
",tmx);
   }
   int rev[maxn];
   LL val[maxn];
   LL sum[maxn];
   LL num[maxn];
   LL mx[maxn];
   LL rx[maxn];
   LL lx[maxn];
   LL cg[maxn];
}spt;
int n , m; 
char str[100];
int ta,tb;
LL tc;
int main(){
  //freopen("in","r",stdin);
  // freopen("output","w",stdout);
    spt.init();
    scanf("%d %d",&n,&m);
    spt.insert(0,n);
    while(m--){
        scanf("%s",str);
        if(str[0] == 'G'){
            scanf("%d %d",&ta,&tb);
            spt.getsum(ta,tb);
        }else if(str[0] == 'I'){
            scanf("%d %d",&ta,&tb);
            spt.insert(ta,tb);
        }else if(str[0] == 'D'){
            scanf("%d %d",&ta,&tb);
            spt.Del(ta,tb);
        }else if(str[0] == 'M' && str[2] == 'K'){
            scanf("%d %d %d",&ta,&tb,&tc);
            spt.make(ta,tb,tc);
        }else if(str[0] == 'R'){
            scanf("%d %d",&ta,&tb);
            spt.flip(ta,tb);
        }else {
        //    spt.debug(spt.root);
            spt.maxsum();
        /*spt.debug(spt.root);
        printf("
");
        spt.print(spt.root);
        printf("
");
            spt.maxsum();*/
        }
    }
return 0;
}