1-binary_tree_insert_left.c

#include "binary_trees.h"

/**
 * binary_tree_insert_left - inserts a node as the left-child of another node
 *
 * @parent: a pointer to the node to insert the left-child in
 * @value: value to store in the new node
 *
 * Return: a pointer to the created node, or NULL on failure,
 * or if parent is NULL
 *
 * if parent already has a left-child, the new node must take its place,
 * and the old left-child must be set as the left-child of the new node.
 */
binary_tree_t *binary_tree_insert_left(binary_tree_t *parent, int value)
{
	binary_tree_t *new_node;

	if (parent == NULL)
		return (NULL);
	new_node = binary_tree_node(parent, value);
	if (new_node == NULL)
		return (NULL);

	new_node->left = parent->left;
	if (parent->left != NULL)
		parent->left->parent = new_node;
	parent->left = new_node;
	return (new_node);
}