题解 | #二叉树的后序遍历#

C++代码：

class Solution {
private:
    vector<int> ans;
public:
    vector<int> postorderTraversal(TreeNode* root) {
        backTrack(root);
        return ans;
    }
    void backTrack(TreeNode *root) {
        if (root) {
            backTrack(root->left);
            backTrack(root->right);
            ans.push_back(root->val);
        }
    }
};