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Leetcode94.cpp
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76 lines (61 loc) · 2.32 KB
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// Leetcode94.cpp : This file contains the 'main' function. Program execution begins and ends there.
//
#include <iostream>
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
// vector<int> inorder;
// vector<int> inorderTraversal(TreeNode* root) {
// inorderTraversalRecursion(root);
// return inorder;
// }
// void inorderTraversalRecursion(TreeNode* root) {
// if(!root) return;
// inorderTraversalRecursion(root->left);
// inorder.push_back(root->val);
// inorderTraversalRecursion(root->right);
// }
vector<int> inorderTraversal(TreeNode* root) {
vector<int> inorder;
if (!root) return inorder;
stack<pair<TreeNode*, int>> stTree; //pair<TreeNode*, int> pointrr to current node, flag to indicate if the left/right node is in the stack
stTree.push({ root, 0 });
while (!stTree.empty())
{
if (stTree.top().second == 0)
{
auto temp = stTree.top();
stTree.pop();
if (temp.first->right != nullptr) stTree.push({ temp.first->right, 0 });
stTree.push(temp); stTree.top().second = 1;
if (temp.first->left != nullptr) stTree.push({ temp.first->left, 0 });
}
else
{
inorder.push_back(stTree.top().first->val);
stTree.pop();
}
}
return inorder;
}
int main()
{
std::cout << "Hello World!\n";
}
// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu
// Tips for Getting Started:
// 1. Use the Solution Explorer window to add/manage files
// 2. Use the Team Explorer window to connect to source control
// 3. Use the Output window to see build output and other messages
// 4. Use the Error List window to view errors
// 5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
// 6. In the future, to open this project again, go to File > Open > Project and select the .sln file