AlgorithmNuggets/ProblemSolving/constructStringFromBinaryTree/other_method.py at master · srixivas/AlgorithmNuggets · GitHub

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# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def tree2str(self, t):
        """
        :type t: TreeNode
        :rtype: str
        """

        def preOrder(t):

            if not t:
                return ""

            result.append(str(t.val))

            # when t.left is null and t.right exists
            if t.right and not t.left:
                result.append("()(")
                preOrder(t.right)
                result.append(")")
            else:
                if t.left:
                    result.append("(")
                    preOrder(t.left)
                    result.append(")")
                if t.right:
                    result.append("(")
                    preOrder(t.right)
                    result.append(")")

        result = []
        preOrder(t)
        print result
        return "".join(result)