[leetcode] Binary Tree Level Order Traversal-优快云博客

本文链接：https://blog.youkuaiyun.com/mungco/article/details/10078099

本文详细介绍了如何实现二叉树的层次遍历，包括使用队列进行节点的逐层遍历，并提供了实例代码来展示整个过程。

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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]
]

confused what "{1,#,2,3}" means? > read more on how binary tree is serialized on OJ.

class Solution {
public:
    vector<vector<int> > levelOrder(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        queue<TreeNode *> level;
        vector<vector<int> > container;
        TreeNode *iroot;
        vector<int> inner;
        if(root==NULL)
            return container;
        level.push(root);
        level.push(NULL);
        inner.push_back(root->val);
        container.push_back(inner);
        inner.clear();
        while(!level.empty()){
            iroot=level.front();
            level.pop();
            if(iroot==NULL){
                if(inner.size()==0)
                    break;
                container.push_back(inner);
                inner.clear();
                level.push(NULL);
            }
            else{
                if(iroot->left){
                    inner.push_back(iroot->left->val);
                    level.push(iroot->left);
                }
                if(iroot->right){
                    inner.push_back(iroot->right->val);
                    level.push(iroot->right);
                }
            }
        }
        return container;
    }
};