Leetcode - 617. Merge Two Binary Trees

문제

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LeetCode

풀이

if문이 너무 많아 지저분한 풀이.

class Solution:
    def mergeTrees(self, root1: TreeNode, root2: TreeNode) -> TreeNode:
        def merge(node1, node2):
            if node2 is None:
                return

            node1.val += node2.val

            if node1.left is None:
                node1.left = node2.left
            else:
                merge(node1.left, node2.left)

            if node1.right is None:
                node1.right = node2.right
            else:
                merge(node1.right, node2.right)

        if root1 and root2:
            merge(root1, root2)
        return root1

기존 트리를 사용하지 않아야 간결하게 풀 수 있겠다는 아이디어로 구현한 풀이. 결과적으로 책의 풀이와 같다.

class Solution:
    def mergeTrees(self, root1: TreeNode, root2: TreeNode) -> TreeNode:
        def merge(node1, node2):
            if node1 and node2:
                node = TreeNode(node1.val + node2.val)
                node.left = merge(node1.left, node2.left)
                node.right = merge(node1.right, node2.right)
                return node
            else:
                return node1 or node2

        return merge(root1, root2)