LeetCode/Post_Order_Binary_tree.cpp at main · Requasar/LeetCode · GitHub

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/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    void sol(TreeNode* root, vector<int> &ans){
        if(root == nullptr)
            return;
        sol(root->left,ans);
        sol(root->right,ans);
        ans.push_back(root->val);

    }
    vector<int> postorderTraversal(TreeNode* root) {
        vector<int> ans;
        sol(root,ans);
        return ans;
    }
};