Discussion of Leetcode 109 with the peer from 6:00 PM - 7:30 PM

Discussion of Leetcode 109

private ListNode node;  <-   linked list 

public TreeNode sortedListToBST(ListNode head) {
	if(head == null){
		return null;
	}
	
	int size = 0;
	ListNode runner = head;
	node = head;
	
	while(runner != null){  // 152 - 155 - travel list - find how many nodes
		runner = runner.next;
		size ++; 
	}// here we get size...
	
	return inorderHelper(0, size - 1);
}

public TreeNode inorderHelper(int start, int end){
	if(start > end){
		return null;
	}
	
	int mid = start + (end - start) / 2;
	TreeNode left = inorderHelper(start, mid - 1);
	
	TreeNode treenode = new TreeNode(node.val);  // <- if there is only one, put node definitely to our root node <- 
	treenode.left = left;
	node = node.next;    //  <-  move linked list to next node <-  mapping inorder traversal  Left, root, right , only have one node

	TreeNode right = inorderHelper(mid + 1, end);
	treenode.right = right;
	
	return treenode;
}