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数据结构实验之查找二：平衡二叉树

Time Limit: 400ms   Memory limit: 65536K  有疑问？点这里^_^

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

提示

代码实现：

#include <bits/stdc++.h>
using namespace std;

typedef int element;

struct Tree
{
    element data;
    int deep;
    Tree *lchild,*rchild;
};

int Max(int a,int b)
{
    return a>b ? a:b;
}

int Deep(Tree *T)
{
    if(!T)
        return -1;
    else
        return T->deep;
}

Tree *LL(Tree *T)///右旋
{
    Tree *p = T->lchild;
    T->lchild = p->rchild;
    p->rchild = T;
    p->deep = Max(Deep(p->lchild),Deep(p->rchild))+1;
    T->deep = Max(Deep(T->lchild),Deep(T->rchild))+1;
    return p;
}

Tree *RR(Tree *T)///左旋
{
    Tree *p = T->rchild;
    T->rchild = p->lchild;
    p->lchild = T;
    p->deep = Max(Deep(p->lchild),Deep(p->rchild))+1;
    T->deep = Max(Deep(T->lchild),Deep(T->rchild))+1;
    return p;
}

Tree *LR(Tree *T)///先左旋后右旋
{
    T->lchild = RR(T->lchild);
    return LL(T);
}

Tree *RL(Tree *T)///先右旋后左旋
{
    T->rchild = LL(T->rchild);
    return RR(T);
}

Tree *Creat(Tree *T,int n)
{
    if(!T)
    {
        T = new Tree;
        T->data = n;
        T->deep = 0;
        T->lchild = T->rchild = NULL;
    }
    else
    {
        if(n < T->data)
        {
            T->lchild = Creat(T->lchild,n);
            if(Deep(T->lchild)-Deep(T->rchild) > 1)
            {
                if(T->lchild->data > n)
                    T = LL(T);
                else
                    T = LR(T);
            }
        }
        else if(n > T->data)
        {
            T->rchild = Creat(T->rchild,n);
            if(Deep(T->rchild)-Deep(T->lchild) > 1)
            {
                if(T->rchild->data < n)
                    T = RR(T);
                else
                    T = RL(T);
            }
        }
    }
    T->deep = Max(Deep(T->lchild),Deep(T->rchild)) + 1;
    return T;
}

int main()
{
    int n,m;
    Tree *T = NULL;
    scanf("%d",&n);
    for(int i = 0;i < n;i++)
    {
        scanf("%d",&m);
        T = Creat(T,m);
    }
    printf("%d\n",T->data);
    return 0;
}