IT公司100题-11-求二叉树中节点的最大距离

问题描述：

写程序，求一棵二叉树中相距最远的两个节点之间的距离。

10
/     \
6      14
/   \   /   \
4    8 12    16

分析：

二叉树中最远的两个节点，要么是根和一个叶子节点，要么是两个叶子节点。

代码实现：

 // 11.cc
 #include <iostream>
 using namespace std;

 typedef struct BSTreeNode {
     int data;
     BSTreeNode *left;
     BSTreeNode *right;
 } tree_node;

 // 创建二元查找树
 void add_BSTree_node(tree_node* &p_current, int data) {
     if (NULL == p_current) {
         tree_node *node = new tree_node();
         node->left = NULL;
         node->right = NULL;
         node->data = data;
         p_current = node;
     } else {
         if (p_current->data > data)
             add_BSTree_node(p_current->left, data);
         else if (p_current->data < data)
             add_BSTree_node(p_current->right, data);
         else
             cout << "The data has already in the tree.";
     }
 }

 int helper(tree_node* root, int& depth) {
     if (!root) {
         depth = ;
         return ;
     }
     int ld, rd;
     int max_left = helper(root->left, ld);
     int max_right = helper(root->right, rd);
     depth = max(ld, rd) + ;
     return max(max_left, max(max_right, ld + rd));
 }

 // 查找最大距离
 int max_distance(tree_node* root) {
     int depth;
     return helper(root, depth);
 }

 int main() {
     tree_node *root = NULL;
     add_BSTree_node(root, );
     add_BSTree_node(root, );
     add_BSTree_node(root, );
     add_BSTree_node(root, );
     add_BSTree_node(root, );
     add_BSTree_node(root, );
     add_BSTree_node(root, );
     add_BSTree_node(root, );

     int depth;
     int max_d = max_distance(root);
     cout << max_d << endl;
 }