Ancestor matrix for binary tree

// C++ program to construct ancestor matrix for 
// given tree. 
#include<bits/stdc++.h> 
using namespace std; 
#define MAX 100 
  
/* A binary tree node */
struct Node 
{ 
    int data; 
    Node *left, *right; 
}; 
  
// Creating a global boolean matrix for simplicity 
bool mat[MAX][MAX]; 
  
// anc[] stores all ancestors of current node.  This 
// function fills ancestors for all nodes. 
// It also returns size of tree.  Size of tree is 
// used to print ancestor matrix. 
int ancestorMatrixRec(Node *root, vector<int> &anc) 
{ 
    /* base case */
    if (root == NULL) return 0;; 
  
    // Update all ancestors of current node 
    int data = root->data; 
    for (int i=0; i<anc.size(); i++) 
       mat[anc[i]][data] = true; 
  
    // Push data to list of ancestors 
    anc.push_back(data); 
  
    // Traverse left and right subtrees 
    int l = ancestorMatrixRec(root->left, anc); 
    int r = ancestorMatrixRec(root->right, anc); 
  
    // Remove data from list the list of ancestors 
    // as all descendants of it are processed now. 
    anc.pop_back(); 
  
    return l+r+1; 
} 
  
// This function mainly calls ancestorMatrixRec() 
void ancestorMatrix(Node *root) 
{ 
    // Create an empty ancestor array 
    vector<int> anc; 
  
    // Fill ancestor matrix and find size of 
    // tree. 
    int n = ancestorMatrixRec(root, anc); 
  
    // Print the filled values 
    for (int i=0; i<n; i++) 
    { 
        for (int j=0; j<n; j++) 
            cout << mat[i][j] << " "; 
        cout << endl; 
    } 
} 
  
/* Helper function to create a new node */
Node* newnode(int data) 
{ 
    Node* node = new Node; 
    node->data = data; 
    node->left = node->right = NULL; 
    return (node); 
} 
  
/* Driver program to test above functions*/
int main() 
{ 
    /* Construct the following binary tree 
                5 
              /   \ 
            1      2 
          /  \    / 
         0    4  3    */
    Node *root        = newnode(5); 
    root->left        = newnode(1); 
    root->right       = newnode(2); 
    root->left->left  = newnode(0); 
    root->left->right = newnode(4); 
    root->right->left = newnode(3); 
  
    ancestorMatrix(root); 
  
    return 0; 
}