Flatten Binary Tree to Linked List

将左子树移到右边循环即可

public class Solution {
    public void flatten(TreeNode root) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        while(root != null){
            if(root.left != null){
                TreeNode right = root.right;
                TreeNode left = root.left;
                root.left = null;
                root.right = left;
                while(left.right!=null)
                    left = left.right;
                left.right = right;
            }
            root = root.right;
        }
    }

}