94 Binary Tree Inorder Traversal

1 题目

Given a binary tree, return the inorder traversal of its nodes' values.

2 尝试解

class Solution {
public:
    vector<int> inorderTraversal(TreeNode* root) {
        vector<int> result;
        inorderTree(root,result);
        return result;
    }
    void inorderTree(TreeNode* root,vector<int>& saver){
        if(root == NULL) { return;}
        if(root->right == NULL && root->left == NULL) 
        {saver.push_back(root->val);return;}
        inorderTree(root->left,saver);
        saver.push_back(root->val);
        inorderTree(root->right,saver);
    }
};

3 标准解

class Solution {
public:
    vector<int> inorderTraversal(TreeNode* root) {
        vector<int> nodes;
        inorder(root, nodes);
        return nodes;
    }
private:
    void inorder(TreeNode* root, vector<int>& nodes) {
        if (!root) {
            return;
        }
        inorder(root -> left, nodes);
        nodes.push_back(root -> val);
        inorder(root -> right, nodes);
    }
};