【LeetCode 28】102.二叉树的层序遍历

class Solution {
public:
    vector<vector<int>> levelOrder(TreeNode* root) {
        queue<TreeNode*> que;
        if(root!=NULL)
        {
            que.push(root);
        }
        vector<vector<int>> result;//result二维向量数组
        while(!que.empty())
        {
            int size=que.size();
            vector<int> vec;
            for(int i=0;i<size;i++)
            {
                TreeNode *node=que.front();
                que.pop();
                vec.push_back(node->val);
                if(node->left) que.push(node->left);
                if(node->right) que.push(node->right);
            }
            result.push_back(vec);
        }
        return result;
    }
};