Iterative Inorder Traversal - Leetcode

class Solution { public: vector<int> inorderTraversal(TreeNode* root) { //first, we create a stack stack<TreeNode*>st; //create a node and assign it to root TreeNode*node = root; //declare a vector which stores inorder vector<int>inorder; while(true){ //if the node that is the root is not null, we take that and insert it into stack if(node != NULL){ st.push(node); //after pushing into stack, move to the left node = node->left; } else{ //if you traverse a tree and end up getting null, this is what you need to do //if stack is empty there are no nodes to travel if(st.empty() == true) break; //else if the st is not empty, whatever is at the top we will take it node = st.top(); st.pop(); //and this is eventually inorder inorder.push_back(node->val); node = node->right; } } return inorder; } }; //TC :O(n) , as we traverse every node // SC :O(h) , height of the binary tree, in worst case it is skewed tree