Level_Order_Traversal.cpp

#include <bits/stdc++.h>
/************************************************************

    Following is the BinaryTreeNode class structure

    template <typename T>
    class BinaryTreeNode {
       public:
        T val;
        BinaryTreeNode<T> *left;
        BinaryTreeNode<T> *right;

        BinaryTreeNode(T val) {
            this->val = val;
            left = NULL;
            right = NULL;
        }
    };

************************************************************/

void getLevelOrder(BinaryTreeNode<int> *root, vector<int> &ans)
{
    if (root == NULL)
    {
        return;
    }

    queue<BinaryTreeNode<int> *> q;
    q.push(root);

    while (!q.empty())
    {
        BinaryTreeNode<int> *front = q.front();
        q.pop();

        ans.push_back(front->val);

        if (front->left != NULL)
        {
            q.push(front->left);
        }
        if (front->right != NULL)
        {
            q.push(front->right);
        }
    }
}

vector<int> getLevelOrder(BinaryTreeNode<int> *root)
{
    //  Write your code here.
    vector<int> ans;
    getLevelOrder(root, ans);
    return ans;
}