C 语言

关注公众号 jb51net

关闭
首页 > 软件编程 > C 语言 > C++实现二叉树的最大深度

C++实现LeetCode(104.二叉树的最大深度)

作者:Grandyang

这篇文章主要介绍了C++实现LeetCode(104.二叉树的最大深度),本篇文章通过简要的案例,讲解了该项技术的了解与使用,以下就是详细内容,需要的朋友可以参考下

[LeetCode] 104. Maximum Depth of Binary Tree 二叉树的最大深度

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Note: A leaf is a node with no children.

Example:

Given binary tree [3,9,20,null,null,15,7],

    3
/ \
9  20
/  \
15   7

return its depth = 3.

求二叉树的最大深度问题用到深度优先搜索 Depth First Search,递归的完美应用,跟求二叉树的最小深度问题原理相同,参见代码如下:

C++ 解法一:

class Solution {
public:
    int maxDepth(TreeNode* root) {
        if (!root) return 0;
        return 1 + max(maxDepth(root->left), maxDepth(root->right));
    }
};

Java 解法一:

public class Solution {
    public int maxDepth(TreeNode root) {
        return root == null ? 0 : (1 + Math.max(maxDepth(root.left), maxDepth(root.right)));
    }
}

我们也可以使用层序遍历二叉树,然后计数总层数,即为二叉树的最大深度,注意 while 循环中的 for 循环的写法有个 trick,一定要将 q.size() 放在初始化里,而不能放在判断停止的条件中,因为q的大小是随时变化的,所以放停止条件中会出错,参见代码如下:

C++ 解法二:

class Solution {
public:
    int maxDepth(TreeNode* root) {
        if (!root) return 0;
        int res = 0;
        queue<TreeNode*> q{{root}};
        while (!q.empty()) {
            ++res;
            for (int i = q.size(); i > 0; --i) {
                TreeNode *t = q.front(); q.pop();
                if (t->left) q.push(t->left);
                if (t->right) q.push(t->right);
            }
        }
        return res;
    }
};

Java 解法二:

public class Solution {
    public int maxDepth(TreeNode root) {
        if (root == null) return 0;
        int res = 0;
        Queue<TreeNode> q = new LinkedList<>();
        q.offer(root);
        while (!q.isEmpty()) {
            ++res;
            for (int i = q.size(); i > 0; --i) {
                TreeNode t = q.poll();
                if (t.left != null) q.offer(t.left);
                if (t.right != null) q.offer(t.right);
            }
        }
        return res;
    }
}

Github 同步地址:

https://github.com/grandyang/leetcode/issues/104

类似题目:

Balanced Binary Tree

Minimum Depth of Binary Tree

Maximum Depth of N-ary Tree

参考资料:

https://leetcode.com/problems/maximum-depth-of-binary-tree/

https://leetcode.com/problems/maximum-depth-of-binary-tree/discuss/34207/my-code-of-c-depth-first-search-and-breadth-first-search

到此这篇关于C++实现LeetCode(104.二叉树的最大深度)的文章就介绍到这了,更多相关C++实现二叉树的最大深度内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家!

您可能感兴趣的文章:
阅读全文