Leetcode: Binary Tree Level Order Traversal: Two Queue

最新推荐文章于 2020-06-07 02:08:27 发布

chenhaoliu

最新推荐文章于 2020-06-07 02:08:27 发布

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本文链接：https://blog.youkuaiyun.com/chenhaoliu/article/details/8479220

本文介绍了一种使用C++实现二叉树层次遍历的方法，通过队列结构进行节点的逐层访问，返回每个层次的节点值。

/**
 * 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) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<vector<int> > vv;
        if(!root)
            return vv;
        vv.clear();
        vector<int> v;
        v.clear();
        queue<TreeNode*> current,next;
        current.push(root);
        while(!current.empty()){
            TreeNode* tmp=current.front();
            current.pop();
            v.push_back(tmp->val);
            if(tmp->left)
                next.push(tmp->left);
            if(tmp->right)
                next.push(tmp->right);
            if(current.empty()){
                vv.push_back(v);
                v.clear();
                swap(current,next);
            }
        }
        return vv;
    }
};