数据结构实验之查找二：平衡二叉树

数据结构实验之查找二：平衡二叉树

Time Limit: 400MS Memory limit: 65536K

题目描述

根据给定的输入序列建立一棵平衡二叉树，求出建立的平衡二叉树的树根。

输入

输入一组测试数据。数据的第1行给出一个正整数N(n <= 20)，N表示输入序列的元素个数；第2行给出N个正整数，按数据给定顺序建立平衡二叉树。

输出

输出平衡二叉树的树根。

示例输入

5
88 70 61 96 120

示例输出

70

#include <bits/stdc++.h>

using namespace std;

struct node
{
int data;
int h;
node *l, *r;
};
int Deep(node *head)
{
if(!head)
return -1;
return head->h;
}

node *Left(node *head)
{
node *q = head->l;
head->l = q->r;
q->r = head;
q->h = max(Deep(q->l),Deep(q->r))+1;
head->h = max(Deep(head->l),Deep(head->r))+1;
return q;
}
node *Right(node *head)
{
node *q = head->r;
head->r = q->l;
q->r = head;
q->h = max(Deep(q->l),Deep(q->r))+1;
head->h = max(Deep(head->l),Deep(head->r))+1;
return q;
}
node *LLeft(node *head)
{
head->l = Right(head->l);
return Left(head);
}

node *RRight(node *head)
{
head->r = Left(head->r);
return Right(head);
}

node *Inster(node *head, int x)
{
if(!head)
{
head = new node;
head->l = NULL, head->r = NULL;
head->data = x;
head->h = 0;
}
else if(x < head->data)
{
head->l = Inster(head->l, x);
if(Deep(head->l) - Deep(head->r) > 1)
{
if(x < head->l->data)
head = Left(head);
else
head = LLeft(head);
}
}
else
{
head->r = Inster(head->r, x);
if(Deep(head->r) - Deep(head->l) > 1)
{
if(x < head->r->data)
head = RRight(head);
else
head = Right(head);
}
}
head->h = max(Deep(head->l),Deep(head->r))+1;
return head;
}

int main()
{
int n, x;
cin>>n;
node *head = NULL;
for(int i=0; i<n; i++)
{
cin>>x;
head = Inster(head,x);
}
cout<<head->data<<endl;
return 0;
}