代码随想录：二叉树的层序遍历

代码随想录：二叉树的层序遍历

本来想用java写，但是太多代码细节不知道了，还是算了

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left),
 * right(right) {}
 * };
 */
class Solution {
public:
    vector<vector<int>> levelOrder(TreeNode* root) {
        vector<vector<int>> res;
        if (!root) return res;
        queue<TreeNode*> que;
        que.push(root);
        while (!que.empty()) {
            vector<int> temp;
            int size = que.size();
            while (size > 0) {
                TreeNode* target = que.front();
                que.pop();
                temp.push_back(target->val);
                if(target->left)que.push(target->left);
                if(target->right)que.push(target->right);
                size--;
            }
            res.push_back(temp);
        }
        return res;
    }
};