inorder_traversal.cpp

#include <stdio.h>
using namespace std;

// Tree Node
struct Node {
    int data;
    Node *left;
    Node *right;

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

vector<int> inOrder(struct Node *root);

// Function to Build Tree
Node* buildTree(string str)
{
    // Corner Case
    if(str.length() == 0 || str[0] == 'N')
        return NULL;

    // Creating vector of strings from input
    // string after spliting by space
    vector<string> ip;

    istringstream iss(str);
    for(string str; iss >> str; )
        ip.push_back(str);

    // Create the root of the tree
    Node* root = new Node(stoi(ip[0]));

    // Push the root to the queue
    queue<Node*> queue;
    queue.push(root);

    // Starting from the second element
    int i = 1;
    while(!queue.empty() && i < ip.size()) {

        // Get and remove the front of the queue
        Node* currNode = queue.front();
        queue.pop();

        // Get the current node's value from the string
        string currVal = ip[i];

        // If the left child is not null
        if(currVal != "N") {

            // Create the left child for the current node
            currNode->left = new Node(stoi(currVal));

            // Push it to the queue
            queue.push(currNode->left);
        }

        // For the right child
        i++;
        if(i >= ip.size())
            break;
        currVal = ip[i];

        // If the right child is not null
        if(currVal != "N") {

            // Create the right child for the current node
            currNode->right = new Node(stoi(currVal));

            // Push it to the queue
            queue.push(currNode->right);
        }
        i++;
    }

    return root;
}


int main() {
    int t;
    string  tc;
    getline(cin,tc);
    t=stoi(tc);
    while(t--)
    {
        string s;
        getline(cin,s);
        Node* root = buildTree(s);

        vector <int> res = inOrder(root);
        for (int i = 0; i < res.size (); i++)
            cout << res[i] << " ";
        cout << endl;
    }
    return 0;
}


// } Driver Code Ends


/* A binary tree node has data, pointer to left child
   and a pointer to right child  
struct Node {
    int data;
    Node *left;
    Node *right;

    Node(int val) {
        data = val;
        left = right = NULL;
    }
}; */


// Return a vector containing the inorder traversal of the tree

void inorderFun(Node *root, vector <int> &res)
{
if (root == NULL)return;
inorderFun(root->left, res);
res.push_back (root->data);
inorderFun(root->right, res);
}
vector <int> inOrder(struct Node *root) {
vector <int> res;
inorderFun(root, res);
return res;
}