LeetCode145. Binary Tree Postorder Traversal

LeetCode145. Binary Tree Postorder Traversal

題目描述：

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

For example:

Given binary tree {1,#,2,3},

   1
    \
     2
    /
   3

return [3,2,1].

分析：遞歸求解。。。

c++代碼：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
private:
    vector<int> result;
public:
    vector<int> postorderTraversal(TreeNode* root) {
        result.clear();
        postorder(root);
        return result;
    }
    void postorder(TreeNode *root)
    {
        if(root==NULL) return;
        postorder(root->left);
        postorder(root->right);
        result.push_back(root->val);
    }
};

python代碼：

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def postorderTraversal(self, root):
        """
        :type root: TreeNode
        :rtype: List[int]
        """
        self.result=[]
        self.postorder(root)
        return self.result
    def postorder(self,root):
        if root==None:
            return
        self.postorder(root.left)
        self.postorder(root.right)
        self.result.append(root.val)

（完）