Boundary Traversal of Binary Tree

/* A binary tree Node
struct Node
{
    int data;
    Node* left, * right;
}; */

class Solution {
public:

    void leftTraversal(Node* root, vector<int> &ans){
        if((root == NULL) || (root->right == NULL && root->left == NULL)){
            return ;
        }
        ans.push_back(root->data);
        if(root->left){
            leftTraversal(root->left,ans);
        }
        else{
            leftTraversal(root->right,ans);
        }
    }
    
    void leafTraversal(Node* root, vector<int> &ans){
        if(root == NULL){
            return;
        }
        if(root->left == NULL && root->right == NULL){
            ans.push_back(root->data);
            return;
        }
        leafTraversal(root->left,ans);
        leafTraversal(root->right,ans);
    }
    
    void rightTraversal(Node* root,vector<int> &ans){
        //base case
        if((root == NULL) || (root->left == NULL && root->right == NULL)){
            return;
        }
        if(root->right){
            rightTraversal(root->right,ans);
        }
        else{
            rightTraversal(root->left,ans);
        }
        ans.push_back(root->data);
    }
    
    vector <int> boundary(Node *root)
    {
        vector<int> ans;
        if(root == NULL){
            return ans;
        }
        ans.push_back(root->data);
        
        //left part store
        leftTraversal(root->left,ans);
        
        //traverse leaf node
        //traverse left sub tree
        leafTraversal(root->left,ans);
        //traverse right sub tree
        leafTraversal(root->right,ans);
        
        //store right part
        rightTraversal(root->right,ans);
        
        return ans;
        
    }
};