编程之美--求二叉树中节点的最大距离

#include <iostream>
#include "vld.h"
using namespace std;

struct Node
{
char val;
int max_right;
int max_left;
Node *right;
Node *left;
Node(int ch)
{
val = ch;
max_left = 0;
max_right = 0;
right = NULL;
left = NULL;
}
};
void bulid(Node **root);
void print_node(Node *root);
void delete_tree(Node *root);
void find_max_distance(Node *root,int &max_distance);
int main()
{
Node *root = NULL;
bulid(&root);
if(root == NULL) cout<<"NULL！"<<endl;
cout<<"先序遍历！"<<endl;
print_node(root);
cout<<"节点最大距离！"<<endl;
int max_dis = 0;
find_max_distance(root,max_dis);
cout<<endl<<max_dis<<endl;

delete_tree(root);
return 0;
}

void bulid(Node **root)
{
char ch;
cin>>ch;
if (ch == '0')
{
root = NULL;
}
else
{
*root = new Node(ch);
bulid(&((*root)->left));
bulid(&((*root)->right));
}
}

void print_node(Node *root)
{
if(root == NULL) return ;

cout<<root->val<<" ";
print_node(root->left);
print_node(root->right);

}

void delete_tree(Node *root)
{
if(root == NULL) return ;

delete_tree(root->left);
delete_tree(root->right);
delete root;

}

void find_max_distance(Node *root,int &max_distance)
{
if (root == NULL)
{
return ;
}

if (root->left == NULL)
{
root->max_left = 0;
}
if (root->right == NULL)
{
root->max_right = 0;
}

if (root->left != NULL)
{
find_max_distance(root->left,max_distance);

if (root->left->max_left > root->left->max_right)
{
root->max_left = root->left->max_left + 1;
}
else
{
root->max_left = root->left->max_right + 1;
}
}

if (root->right != NULL)
{
find_max_distance(root->right,max_distance);

if (root->right->max_left > root->right->max_right)
{
root->max_right = root->right->max_left + 1;
}
else
{
root->max_right = root->right->max_right + 1;
}
}

if (max_distance < root->max_left + root->max_right)
{
max_distance = root->max_left + root->max_right;
}

}