题解 | #求二叉树的层序遍历#

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 *	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > levelOrder(TreeNode* root) {
        // write code here
        queue<TreeNode*> que;
        vector<vector<int> >result;
        if(root != NULL)
        que.push(root);
        while(!que.empty())
        {
            size_t size = que.size();
            vector<int> vec;
            while(size--)
            {
                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;
    }
};