04-树5 Root of AVL Tree

题意

构造一棵AVL树，输出根结点的值。

参考代码

#include <bits/stdc++.h>
using namespace std;
typedef struct Node{
    int v,h;
    struct Node *l,*r;
}*tree;
int GetHigh(tree t){
    if (t==NULL) return 0;
    return max(GetHigh(t->l),GetHigh(t->r))+1;
}
tree RotateLL(tree &A){
    tree B=A->l;
    A->l=B->r;
    B->r=A;
    B->h=max(GetHigh(B->l),GetHigh(B->r))+1;
    A->h=max(GetHigh(A->l),GetHigh(B->r))+1;
    return B;
}
tree RotateRR(tree &A){
    tree B=A->r;
    A->r=B->l;
    B->l=A;
    B->h=max(GetHigh(B->l),GetHigh(B->r))+1;
    A->h=max(GetHigh(A->l),GetHigh(B->r))+1;
    return B;
}
tree RotateLR(tree &A){
    A->l=RotateRR(A->l);
    return RotateLL(A);
}
tree RotateRL(tree &A){
    A->r=RotateLL(A->r);
    return RotateRR(A);
}
tree Insert(tree &t,int x){
    if (t==NULL){
        t=new Node;
        t->v=x;
        t->h=0;
        t->l=t->r=NULL;
        return t;
    }
    if (x<t->v){
        t->l=Insert(t->l,x);
        if (GetHigh(t->l)-GetHigh(t->r)==2){
            if (x<t->l->v) t=RotateLL(t);
            else t=RotateLR(t);
        }
    }
    else{
        t->r=Insert(t->r,x);
        if (GetHigh(t->l)-GetHigh(t->r)==-2){
            if (x>t->r->v) t=RotateRR(t);
            else t=RotateRL(t);
        }
    }
    t->h=max(GetHigh(t->l),GetHigh(t->r))+1;
    return t;
}
int main(){
    int n,x;
    cin>>n;
    tree t=NULL;
    for (int i=0;i<n;i++){
        cin>>x;
        Insert(t,x);
    }
    cout<<t->v<<endl;
    return 0;
}