Leetcode skimming: binary tree 03 (post order traversal of binary tree)

145. Postorder traversal of binary trees

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package com.programmercarl.tree;

import java.util.ArrayList;
import java.util.List;

/** * @ClassName PostorderTraversal * @Descriotion TODO * @Author nitaotao * @Date 2022/7/1 15:27 * @Version 1.0 * 145.  Postorder traversal of binary trees  * https://leetcode.cn/problems/binary-tree-postorder-traversal/ **/
public class PostorderTraversal {
    
    public List<Integer> postorderTraversal(TreeNode root) {
    
        List<Integer> result = new ArrayList<Integer>();
        traversal(root, result);
        return result;
    }

    /** *  After the sequence traversal  * @param root * @param result */
    public void traversal(TreeNode root, List<Integer> result) {
    
        // Determine termination conditions 
        if (root == null) {
    
            return;
        }
        // Left 
        traversal(root.left,result);
        // Right 
        traversal(root.right,result);
        // in 
        result.add(root.val);
    }
}