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BinaryTreePostorderTraversal.cpp
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40 lines (40 loc) · 951 Bytes
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/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<int> postorderTraversal(TreeNode* root) {
stack<TreeNode*> stk;
vector<int> res;
TreeNode* last = NULL;
while (!stk.empty() || root)
{
if (root)
{
stk.push(root);
root = root->left;
}
else
{
TreeNode* node = stk.top();
if (node->right && node->right != last)
{
root = node->right;
}
else
{
res.push_back(node->val);
last = node;
stk.pop();
}
}
}
return res;
}
};