LeetCode 145. Binary Tree Postorder Traversal

Given an input string, reverse the string word by word.

For example,
Given s = “the sky is blue”,
return “blue is sky the”.

分析：后序遍历，左右根～

/**
 * 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:
    vector<int> result;
    vector<int> postorderTraversal(TreeNode* root) {
        dfs(root);
        return result;
    }
    void dfs(TreeNode* root) {
        if(root == NULL) return;
        dfs(root->left);
        dfs(root->right);
        result.push_back(root->val);
    }
};

/**

* 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:

vector<int> result;

vector<int> postorderTraversal(TreeNode* root) {

dfs(root);

return result;

}

void dfs(TreeNode* root) {

if(root == NULL) return;

dfs(root->left);

dfs(root->right);

result.push_back(root->val);

}

};