Tree Node

Binary Tree Representation in C: A tree is represented by a pointer to the topmost node in tree. If the tree is empty, then value of root is NULL.
A Tree node contains following parts.

• Data
• Pointer to left child
• Pointer to right child

struct TreeNode
{
    DataType data;
    struct TreeNode * leftchild;
    struct TreeNode * rightchild;
};

Create a simple tree with 4 nodes in C

typedef struct node
{
     DataType data;//data domain
     struct node *left; //left child
    struct node * right;  // right child
} Node;

// new Tree Node
Node *  newNode(DataType data)
{
     Node * node = (Node*)malloc(sizeof(Node));
     node->data = data;
    node->left = NULL;
    node->right = NULL;
    return node;
}

int main(void)
{
 Node * root  = newNode(1);
 root->left  = newNode(2);
 root->right = newNode(3);
root->left->left = newNode(4);
getchar();
return 0;
}

Created using Python

class Node:
    def __init__(self,key):
        self.left = None
        self.right = None
        self.val = key

root = Node(1)
root.left  = Node(2)
root.right = Node(3)
root.left.left = Node(4)