leetcode #102Binary Tree Level Order Traversal

最新推荐文章于 2020-11-25 22:05:52 发布

原创最新推荐文章于 2020-11-25 22:05:52 发布 · 430 阅读

0 ·

CC 4.0 BY-SA版权

leetcode 专栏收录该内容

2 篇文章

订阅专栏

本文介绍了一种算法，用于实现二叉树的层次遍历并返回各层级节点的值。通过使用队列来跟踪每一层的节点，该算法能够有效地从左到右逐层返回节点值。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).

For example:
Given binary tree {3,9,20,#,#,15,7},

return its level order traversal as:

[
  [3],
  [9,20],
  [15,7]
]
/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    vector<vector<int> > levelOrder(TreeNode *root) {
		vector<vector<int>> result;
		if(root==nullptr)
			return result;
		vector<TreeNode*> v;
		v.push_back(root);
		int curr=0;
		int last=1;
		while(curr<v.size()){
			vector<int> temp; 
			last=v.size();
			while(curr<last){
				temp.push_back(v[curr]->val);
				if(v[curr]->left!=nullptr)
					v.push_back(v[curr]->left);
				if(v[curr]->right!=nullptr)
					v.push_back(v[curr]->right);
				++curr;}
			result.push_back(temp);}
		return result;
        
    }
};