#include<iostream>
#include<algorithm>
#include<queue>
using namespace std;
//5种情况：空树；没有子树；只有左/右子树；有俩子树；
struct BinaryNode {BinaryNode *left;BinaryNode *right;int data;
};
struct BinaryTree {BinaryNode *head;
};
//后序遍历递归
//如果左右子树都存在，则取其最小
//如果左右子树没有其中一个，-->说明此根下有叶子结点。所以取其最大
int getDepth(BinaryNode *node)
{if (node == NULL)return 0;int left_depth = getDepth(node->left);int right_depth = getDepth(node->right);if (left_depth && right_depth)  //左子树和右子树都存在return min(left_depth, right_depth) + 1;elsereturn max(left_depth, right_depth) + 1;
}
//层次遍历，使用队列完成
int getDepth2(BinaryNode *root)
{if (root == NULL)return 0;queue<BinaryNode *>q;q.push(root);int depth = 0;while (!q.empty())   //q存放当前层结点，qt存放下一层结点{queue<BinaryNode *>qt;depth++;while (!q.empty()){BinaryNode *temp = q.front();cout << temp->data << endl;q.pop();if (!temp->left && !temp->right){return depth;}if (temp->left)qt.push(temp->left);  if (temp->right)qt.push(temp->right);}q = qt;}return depth;
}int main()
{/*7/   \8     9/       \4         10/ \2   5	*/BinaryTree btree;BinaryNode node1 = { NULL,NULL,7};BinaryNode node2 = { NULL,NULL,9 };BinaryNode node3 = { NULL,NULL,8 };BinaryNode node4 = { NULL,NULL,4 };BinaryNode node5 = { NULL,NULL,2 };BinaryNode node6 = { NULL,NULL,5 };BinaryNode node7 = { NULL,NULL,10 };btree.head = &(node1);node1.left = &(node3);node1.right = &(node2);node2.right = &(node7);node3.left = &(node4);node4.left = &(node5);node4.right = &(node6);int height = getDepth2(&(node1));cout << height << endl;}

运行结果：