left view cpp

// program to print the left view of the binary tree
#include <iostream>
#include <queue>
#include <map>
#include <list>

using namespace std;

// node class
class node{
public:
    int data;
    node* left;
    node* right;
};

// function that returns a pointer to new node
node* createNode(int element){
    node* temp = (node*) malloc(sizeof(node));
    temp->data = element;
    temp->left = NULL;
    temp->right = NULL;
    return temp;
}

// function to print left view of Tree Recursively
void left_view(node *Node, int level){
    if (Node == NULL)
        return;
    static int max_level = -1;
    list<int> lv;
    if (max_level < level){
        max_level = level;
        cout<<Node->data<<" ";
    }
    left_view(Node->left, level+1);
    left_view(Node->right, level+1);
}


int main() {
    node* head = createNode(1);
    head->left = createNode(2);
    head->right = createNode(3);
    head->left->left = createNode(4);
    head->left->right = createNode(5);
    head->right->right = createNode(6);
    head->left->left->right = createNode(7);
    head->right->right->left = createNode(8);
    head->left->left->right->left = createNode(9);
    head->left->left->right->left->left = createNode(10);
    head->right->right->left->right = createNode(11);

    cout<<"\n\nLeft view of the binary tree is : "<<endl;
    int level = -1;
    left_view(head, 0);
    return 0;
}


/*

Left view of the binary tree is :
1 2 4 7 9 10
Process finished with exit code 0

*/