cousin cpp

// program to find out if 2 nodes are cousins or not
#include <iostream>

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 find and return the level of a node in binary tree
int level_of_node(node* root, int data, int level = -1){
    // if the tree is empty or if we reach a leaf node then return 0
    if (root == NULL){
        return -1;
    }
    if(root->data == data){
        return level+1;
    }

    // check in the left subtree for the element
    // if found then return the level
    int level_node = level_of_node(root->left, data, level + 1);
    if (level_node != -1){
        return level_node;
    }

    // searching for the node in right subtree
    level_node = level_of_node(root->right, data, level + 1);
    return level_node;

}

// function to check if 2 nodes are siblings or not
bool isSibling(node* parent, int n1, int n2){
    if(parent == NULL){
        return false;
    }
    if(parent->left != NULL && parent->right != NULL) {
        return (parent->left->data == n1 && parent->right->data == n2) ||
               (parent->left->data == n2 && parent->right->data == n1);
    }
    return (isSibling(parent->left, n1, n2) ||
            isSibling(parent->right, n1, n2)
    );
}

bool isCousin(node* root, int a, int b){
    if( (level_of_node(root, a) == level_of_node(root, b) && isSibling(root, a, b))){
        return true;
    }
    return false;
}

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<<"Nodes 2 and 3 are siblings : "<<isCousin(head, 2, 3)<<endl;
    cout<<"Nodes 6 and 10 are siblings : "<<isCousin(head, 6, 10)<<endl;
    cout<<"Nodes 7 and 8 are siblings : "<<isCousin(head, 7, 8)<<endl;


}



/*

Nodes 2 and 3 are siblings : 1
Nodes 6 and 10 are siblings : 0
Nodes 7 and 8 are siblings : 0
Process finished with exit code 0

*/