tree-notes/practice.cpp at main · coder-writes/tree-notes · GitHub

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#include<bits/stdc++.h>
usingnamespacestd;
structTreeNode
{
int data;
structTreeNode* left;
structTreeNode* right;

TreeNode(int val)
 {
 data = val;
 left = NULL;
 right = NULL;
 }

};
vector<vector<int>> levelOrderTraversalUsingQueue(TreeNode* root){
 queue<TreeNode*> q;
 vector<vector<int>> result;
if(root==NULL) return result;
 q.push(root);
while(!q.empty()){
 vector<int> level;
int size = q.size();

for(int i=0;i<size;i++){
 TreeNode* node = q.front();
 q.pop();
if(node->left) q.push(node->left);
if(node->right) q.push(node->right);

 level.push_back(node->data);

 }
 result.push_back(level);
 }
return result;
}
vector<int> iterativeInOrderTraversalUsingStack(TreeNode* root){
 vector<int> ans;
if(root==NULL) return ans;
 stack<TreeNode*> st;
 TreeNode* node = root;
while(true){
if(node!=NULL){
 st.push(node);
 node = node->left;
 }
else{
if(st.empty()) break;
 node = st.top();
 st.pop();
 ans.push_back(node->data);
 node = node->right;
 }
 }
return ans;
}


#write a function
intmain(){

structTreeNode* root = newTreeNode(2);
 root->left = newTreeNode(5);
 root->left->left = newTreeNode(4);
 root->left->left->left = newTreeNode(3);
 root->left->left->right = newTreeNode(2);
 root->left->right = newTreeNode(5);
 root->right = newTreeNode(7);
 root->right->left = newTreeNode(9);
 root->right->left->right = newTreeNode(2);
 root->right->left->right->right = newTreeNode(4);
 root->right->left->right->left = newTreeNode(1);
 root->right->left->left = newTreeNode(3);
 root->right->right = newTreeNode(7);


 vector<vector<int>> res = levelOrderTraversalUsingQueue(root);

for(auto &val: res){
for(auto &it: val){
 cout<<it<<"";
 }
 cout<<endl;
 }

for(auto val: iterativeInOrderTraversalUsingStack(root)){
 cout<<val<<"";
 }
}