LeetCode145. Binary Tree Postorder Traversal(hard)

原题地址：https://leetcode.com/problems/binary-tree-postorder-traversal/description/

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题目：
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].

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题解：
单纯的后序遍历，只需再写一个函数进行按后序遍历顺序递归即可

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/** * 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 {public:    void post(TreeNode* root,  vector<int>& pt) {        if (root != nullptr) {            post(root->left, pt);            post(root->right, pt);            pt.push_back(root->val);        }    }    vector<int> postorderTraversal(TreeNode* root) {        vector<int> pt;        post(root, pt);        return pt;    }};

67 / 67 test cases passed.
Status: Accepted
Runtime: 3 ms