题解 | #求二叉树的层序遍历#C++二叉树层次遍历递归解法

/**
 * 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<>>
     */
    int height(TreeNode*root)
    {
        if(root)
        {
            int m=height(root->left);
            int n=height(root->right);
            return max(m,n)+1;
        }
        return 0;
    }
    void answer(TreeNode*root,vector <vector <int>>&ans,int h)
    {
        if(root)
        {
            answer(root->left,ans,h+1);
            ans[h].push_back(root->val);
            answer(root->right,ans,h+1);
        }
    }
    vector<vector<int> > levelOrder(TreeNode* root) 
    {
        int i=0;
        int h=height(root);
        vector <vector <int>>ans(h);
        answer(root,ans,i);
        return ans;
    }
};