Binary Tree Inorder Traversal

最新推荐文章于 2022-03-31 17:31:26 发布

转载最新推荐文章于 2022-03-31 17:31:26 发布 · 266 阅读

本文介绍了一种不使用递归实现二叉树中序遍历的方法。通过迭代方式利用栈来存储节点，并按照中序遍历的顺序访问每个节点。此方法避免了递归带来的栈溢出风险。

Given a binary tree, return the inorder traversal of its nodes' values.

Example:

Input: [1,null,2,3]
   1
    \
     2
    /
   3

Output: [1,3,2]

Follow up: Recursive solution is trivial, could you do it iteratively?

class Solution {
public:
    vector<int> inorderTraversal(TreeNode* root) {
        if(root==NULL)
            return vector<int>();
        vector<int> result;
        vector<TreeNode *> stack;
        stack.push_back(root);
        while(!stack.empty())
        {
            TreeNode *top = stack.back();
            if(top->left!=NULL)
            {
                stack.push_back(top->left);
                top->left = NULL;
            }
            else
            {
                result.push_back(top->val);
                cout<<top->val<<endl;
                stack.pop_back();
                if(top->right!=NULL)
                {
                    stack.push_back(top->right);
                }
            }
        }
        return result;
    }
};