114. Flatten Binary Tree to Linked List

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public void flatten(TreeNode root) {
        if(root == null)
            return;
        
        TreeNode c = root;
        while(c != null)
        {
            if(c.left != null)
            {
                TreeNode rightBranch = c.right;
                TreeNode leftBranch = c.left;
                c.left = null;
                c.right = leftBranch;
                
                TreeNode lastRight = c;
                while(lastRight.right != null)
                {
                    lastRight = lastRight.right;
                }
                lastRight.right = rightBranch;
            }
            c = c.right;
        }
    }
}