题解

1 条题解

  • 0
    @ 2021-06-04 19:48:09
    #include<iostream>
    #include<cstring>
    #include<cstdio>
    #include<cstring>
    using namespace std;
    struct node 
    {
        int data,rev,sum;
        node *son[2],*pre;
        bool judge();
        bool isroot();
        void pushdown();
        void update();
        void setson(node *child,int lr);
    }lct[233];
    int top,a,b;
    node *getnew(int x)
    {
        node *now=lct+ ++top;
        now->data=x;
        now->pre=now->son[1]=now->son[0]=lct;
        now->sum=0;
        now->rev=0;
        return now;
    }
    bool node::judge(){return pre->son[1]==this;}
    bool node::isroot()
    {
        if(pre==lct)return true;
        return !(pre->son[1]==this||pre->son[0]==this);
    }
    void node::pushdown()
    {
        if(this==lct||!rev)return;
        swap(son[0],son[1]);
        son[0]->rev^=1;
        son[1]->rev^=1;
        rev=0;
    }
    void node::update(){sum=son[1]->sum+son[0]->sum+data;}
    void node::setson(node *child,int lr)
    {
        this->pushdown();
        child->pre=this;
        son[lr]=child;
        this->update();
    }
    void rotate(node *now)
    {
        node *father=now->pre,*grandfa=father->pre;
        if(!father->isroot()) grandfa->pushdown();
        father->pushdown();now->pushdown();
        int lr=now->judge();
        father->setson(now->son[lr^1],lr);
        if(father->isroot()) now->pre=grandfa;
        else grandfa->setson(now,father->judge());
        now->setson(father,lr^1);
        father->update();now->update();
        if(grandfa!=lct) grandfa->update();
    }
    void splay(node *now)
    {
        if(now->isroot())return;
        for(;!now->isroot();rotate(now))
        if(!now->pre->isroot())
        now->judge()==now->pre->judge()?rotate(now->pre):rotate(now);
    }
    node *access(node *now)
    {
        node *last=lct;
        for(;now!=lct;last=now,now=now->pre)
        {
            splay(now);
            now->setson(last,1);
        }
        return last;
    }
    void changeroot(node *now)
    {
        access(now)->rev^=1;
        splay(now);
    }
    void connect(node *x,node *y)
    {
        changeroot(x);
        x->pre=y;
        access(x);
    }
    void cut(node *x,node *y)
    {
        changeroot(x);
        access(y);
        splay(x);
        x->pushdown();
        x->son[1]=y->pre=lct;
        x->update();
    }
    int query(node *x,node *y)
    {
        changeroot(x);
        node *now=access(y);
        return now->sum;
    }
    int main()
    {
        scanf("%d%d",&a,&b);
        node *A=getnew(a);
        node *B=getnew(b);
        //连边 Link
            connect(A,B);
        //断边 Cut
            cut(A,B);
        //再连边orz Link again
            connect(A,B);
        printf("%d\n",query(A,B)); 
        return 0;
    }
    
  • 1

信息

ID
1000
难度
1
分类
构造 点击显示
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递交数
8
已通过
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通过率
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