Leetcode之前序中序后序非递归遍历总结

最新推荐文章于 2024-05-04 00:05:00 发布

原创最新推荐文章于 2024-05-04 00:05:00 发布 · 202 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#非递归遍历 #前序遍历 #中序遍历 #后序遍历

Leetcode 专栏收录该内容

23 篇文章

订阅专栏

本文介绍了二叉树的三种遍历方式：前序遍历、中序遍历及后序遍历，并提供了对应的Java代码实现。每种遍历方法都详细解释了其遍历逻辑与步骤。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

前序遍历

public List<Integer> preorderTraversal(TreeNode root) {
    List<Integer> result = new ArrayList<>();
    Stack<TreeNode> stack = new Stack<>();
    TreeNode p = root;
    while(!stack.isEmpty() || p != null) {
        if(p != null) {
            stack.push(p);
            result.add(p.val);  // Add before going to children
            p = p.left;
        } else {
            TreeNode node = stack.pop();
            p = node.right;   
        }
    }
    return result;
}

中序遍历

public List<Integer> inorderTraversal(TreeNode root) {
    List<Integer> result = new ArrayList<>();
    Stack<TreeNode> stack = new Stack<>();
    TreeNode p = root;
    while(!stack.isEmpty() || p != null) {
        if(p != null) {
            stack.push(p);
            p = p.left;
        } else {
            TreeNode node = stack.pop();
            result.add(node.val);  // Add after all left children
            p = node.right;   
        }
    }
    return result;
}

后序遍历

public List<Integer> postorderTraversal(TreeNode root) {
    LinkedList<Integer> result = new LinkedList<>();
    Stack<TreeNode> stack = new Stack<>();
    TreeNode p = root;
    while(!stack.isEmpty() || p != null) {
        if(p != null) {
            stack.push(p);
            result.addFirst(p.val);  // Reverse the process of preorder
            p = p.right;             // Reverse the process of preorder
        } else {
            TreeNode node = stack.pop();
            p = node.left;           // Reverse the process of preorder
        }
    }
    return result;
}