如何用C语言编写程序来计算二叉树的深度？

在C语言中，求二叉树的深度通常通过递归实现。首先检查当前节点是否为空，若为空则返回0。接着递归调用左右子树的深度函数，取较大值并加1（加上当前节点）。C#语言中方法类似，但语法略有不同。

递归方法和迭代方法，下面分别给出C语言和C#语言的实现示例。

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C语言实现

#include <stdio.h>
#include <stdlib.h>
typedef struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
} TreeNode;
int max(int a, int b) {
    return (a > b) ? a : b;
}
int getDepth(TreeNode* root) {
    if (root == NULL) {
        return 0;
    }
    int leftDepth = getDepth(root>left);
    int rightDepth = getDepth(root>right);
    return max(leftDepth, rightDepth) + 1;
}
int main() {
    // 创建一个简单的二叉树进行测试
    TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
    root>val = 1;
    root>left = (TreeNode*)malloc(sizeof(TreeNode));
    root>left>val = 2;
    root>right = (TreeNode*)malloc(sizeof(TreeNode));
    root>right>val = 3;
    root>left>left = NULL;
    root>left>right = NULL;
    root>right>left = NULL;
    root>right>right = NULL;
    printf("The depth of the binary tree is: %dn", getDepth(root));
    // 释放内存
    free(root>left);
    free(root>right);
    free(root);
    return 0;
}

C#语言实现

using System;
public class TreeNode {
    public int val;
    public TreeNode left;
    public TreeNode right;
    public TreeNode(int x) { val = x; }
}
public class Solution {
    public int GetDepth(TreeNode root) {
        if (root == null) {
            return 0;
        }
        int leftDepth = GetDepth(root.left);
        int rightDepth = GetDepth(root.right);
        return Math.Max(leftDepth, rightDepth) + 1;
    }
}
public class Program {
    public static void Main() {
        // 创建一个简单的二叉树进行测试
        TreeNode root = new TreeNode(1);
        root.left = new TreeNode(2);
        root.right = new TreeNode(3);
        root.left.left = null;
        root.left.right = null;
        root.right.left = null;
        root.right.right = null;
        Solution solution = new Solution();
        Console.WriteLine("The depth of the binary tree is: " + solution.GetDepth(root));
    }
}