94. Binary Tree Inorder Traversal

最新推荐文章于 2025-12-06 07:43:37 发布

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本文介绍了一种不使用递归的二叉树中序遍历方法，通过栈来跟踪节点并返回节点值的有序列表。该算法适用于需要节省调用栈空间的应用场景。

problem:

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

For example:
Given binary tree [1,null,2,3],

return [1,3,2].

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

solution:

class Solution {
public:
vector<int> inorderTraversal(TreeNode* root) {
vector<int> rei;
stack<TreeNode *> undone;
TreeNode *pCurrent = root;
while (!undone.empty()|| pCurrent != NULL)
{
if (pCurrent->left != NULL)
{
undone.push(pCurrent);
pCurrent = pCurrent->left;
}
else
{
pCurrent = undone.top();
rei.push_back(pCurrent->val);
pCurrent = pCurrent->right;

}
}
return rei;
}
};