SPOJ4487(Splay树)

题目：http://www.spoj.com/problems/GSS6/

 

题意：给一个长度为n的数组，然后给出Q个4种操作，分别是：删除，插入，替换，查找指定区间连续最大和。

#include <iostream>#include <string.h>#include <stdio.h>using namespace std;const int N = 200005;const int INF = 1<<28;int a[N];struct Node{    int val,sz;    int sum,ml,mr,mc;    Node *pre,*ch[2];};class Splay{    public:    Node *null,*root,*S[N],data[N];    int cnt,top;    Node *getNewNode(int x)    {        Node *p;        if(top) p = S[top--];        else    p = &data[cnt++];        p->val = p->sum = p->ml = p->mr = p->mc = x;        p->sz = 1;        p->ch[0] = p->ch[1] = p->pre = null;        return p;    }    void init()    {        cnt = top = 0;        null = getNewNode(-INF);        null->sum = null->sz = 0;        root = getNewNode(-INF);        root->sum = 0;        root->ch[1] = getNewNode(INF);        root->ch[1]->sum = 0;        root->ch[1]->pre = root;        update(root);    }    void update(Node *p)    {        p->sz = p->ch[0]->sz + p->ch[1]->sz + 1;        p->sum = p->ch[0]->sum + p->ch[1]->sum + p->val;        p->ml = max(p->ch[0]->ml,p->ch[0]->sum + p->val + max(p->ch[1]->ml,0));        p->mr = max(p->ch[1]->mr,p->ch[1]->sum + p->val + max(p->ch[0]->mr,0));        p->mc = max(p->ch[0]->mc,p->ch[1]->mc);        p->mc = max(p->mc,max(p->ch[0]->mr + p->ch[1]->ml,0) + p->val);        p->mc = max(p->mc,max(p->ch[0]->mr,p->ch[1]->ml) + p->val);    }    void rotate(Node *x,int c)    {        Node *y = x->pre;        y->ch[!c] = x->ch[c];        if(x->ch[c] != null)            x->ch[c]->pre = y;        x->pre = y->pre;        if(y->pre != null)        {            if(y->pre->ch[0] == y)                y->pre->ch[0] = x;            else                y->pre->ch[1] = x;        }        x->ch[c] = y;        y->pre = x;        if(y == root)            root = x;        update(y);    }    void splay(Node *x,Node *f)    {        while(x->pre != f)        {            if(x->pre->pre == f)                rotate(x,x->pre->ch[0] == x);            else            {                Node *y = x->pre;                Node *z = y->pre;                if(z->ch[0] == y)                {                    if(y->ch[0] == x)                        rotate(y,1),rotate(x,1);                    else                        rotate(x,0),rotate(x,1);                }                else                {                    if(y->ch[1] == x)                        rotate(y,0),rotate(x,0);                    else                        rotate(x,1),rotate(x,0);                }            }        }        update(x);    }    void select(int k,Node *f)    {        int tmp;        Node *t = root;        while(true)        {            tmp = t->ch[0]->sz;            if(tmp + 1 == k) break;            if(k <= tmp) t = t->ch[0];            else            {                k -= tmp + 1;                t = t->ch[1];            }        }        splay(t,f);    }    void insert(int pos,int val)    {        Node *tmproot = getNewNode(val);        select(pos-1,null);        select(pos,root);        root->ch[1]->ch[0] = tmproot;        tmproot->pre = root->ch[1];        splay(root->ch[1],null);    }    void del(int k)    {        select(k,null);        Node *old_root = root;        root = root->ch[1];        root->pre = null;        select(1,null);        root->ch[0] = old_root->ch[0];        root->ch[0]->pre = root;        update(root);        S[++top] = old_root;    }    void replace(int x,int y)    {        select(x,null);        root->val = y;        update(root);    }    Node *build(int l,int r)    {        if(l>r) return null;        int m = (l + r) >> 1;        Node *p = getNewNode(a[m]);        p->ch[0] = build(l,m-1);        if(p->ch[0] != null)            p->ch[0]->pre = p;        p->ch[1] = build(m+1,r);        if(p->ch[1] != null)            p->ch[1]->pre = p;        update(p);        return p;    }};Splay sp;int main(){    char c;    int n,m,x,y;    sp.init();    scanf("%d",&n);    for(int i = 1; i <= n; i++)        scanf("%d",&a[i]);    Node *troot = sp.build(1,n);    sp.root->ch[1]->ch[0] = troot;    troot->pre = sp.root->ch[1];    sp.update(sp.root->ch[1]);    sp.update(sp.root);    sp.splay(sp.root->ch[1],sp.null);    scanf("%d",&m);    for(int i = 1; i <= m ; i++)    {        scanf(" %c",&c);        if(c == 'I')        {            scanf("%d %d",&x,&y);            sp.insert(++x,y);        }        else if(c == 'D')        {            scanf("%d",&x);            sp.del(++x);        }        else if(c == 'R')        {            scanf("%d %d",&x,&y);            sp.replace(++x,y);        }        else if(c == 'Q')        {            scanf("%d %d",&x,&y);            sp.select(++x - 1,sp.null);            sp.select(++y + 1,sp.root);            printf("%d\n",sp.root->ch[1]->ch[0]->mc);        }    }    return 0;}