【Arai60】23問目 617_Merge Two Binary Trees

arai60/21-29_Tree_BT_BST/23_617_Merge Two Binary Trees/level_1.py

@@ -0,0 +1,42 @@
+# DFS(破壊的)
+class Solution:
+    def mergeTrees(
+        self, root1: Optional[TreeNode], root2: Optional[TreeNode]
+    ) -> Optional[TreeNode]:
+        if not root1 and not root2:
+            return None
+        if not root2:
+            return root1
+        if not root1:
+            return root2
+        root1.val += root2.val
+        root1.left = self.mergeTrees(root1.left, root2.left)
+        root1.right = self.mergeTrees(root1.right, root2.right)
+        return root1
+
+
+# BFS(破壊的)
+class Solution:
+    def mergeTrees(
+        self, root1: Optional[TreeNode], root2: Optional[TreeNode]
+    ) -> Optional[TreeNode]:
+
+        if not root1:
+            return root2
+        if not root2:
+            return root1
+        nodes_queue = deque([(root1, root2)])
+        root1.val += root2.val
+        while nodes_queue:
+            node1, node2 = nodes_queue.popleft()
+            if node1.left and node2.left:
+                node1.left.val += node2.left.val
+                nodes_queue.append((node1.left, node2.left))
+            if not node1.left:
+                node1.left = node2.left
+            if node1.right and node2.right:
+                node1.right.val += node2.right.val
+                nodes_queue.append((node1.right, node2.right))
+            if not node1.right:
+                node1.right = node2.right
+        return root1

arai60/21-29_Tree_BT_BST/23_617_Merge Two Binary Trees/level_2.py

@@ -0,0 +1,46 @@
+# DFS
+# 非破壊的に修正
+class Solution:
+    def mergeTrees(
+        self, root1: Optional[TreeNode], root2: Optional[TreeNode]
+    ) -> Optional[TreeNode]:
+        def helper_merge_trees(node1, node2):
+            if not node1 and not node2:
+                return None
+            if not node2:
+                return node1
+            if not node1:
+                return node2
+            node1.val += node2.val
+            node1.left = helper_merge_trees(node1.left, node2.left)
+            node1.right = helper_merge_trees(node1.right, node2.right)
+            return node1
+
+        sum_tree = deepcopy(root1)
+        return helper_merge_trees(sum_tree, root2)
+
+
+# BFS
+# 非破壊的に修正
+# nodeの結合を関数化
+class Solution:
+    def mergeTrees(
+        self, root1: Optional[TreeNode], root2: Optional[TreeNode]
+    ) -> Optional[TreeNode]:
+
+        def merge_nodes(node1, node2, queue):
+            if node1 and node2:
+                node1.val += node2.val
+                queue.append((node1, node2))
+            if not node1:
+                node1 = node2
+            return node1, queue
+
+        nodes_queue = deque()
+        sum_tree = deepcopy(root1)
+        sum_tree, nodes_queue = merge_nodes(sum_tree, root2, nodes_queue)
+        while nodes_queue:
+            node1, node2 = nodes_queue.popleft()
+            node1.left, nodes_queue = merge_nodes(node1.left, node2.left, nodes_queue)
+            node1.right, nodes_queue = merge_nodes(node1.right, node2.right, nodes_queue)
+        return sum_tree

arai60/21-29_Tree_BT_BST/23_617_Merge Two Binary Trees/level_3.py

@@ -0,0 +1,18 @@
+class Solution:
+    def mergeTrees(
+        self, root1: Optional[TreeNode], root2: Optional[TreeNode]
+    ) -> Optional[TreeNode]:
+        def helper_merge_tree(node1, node2):
+            if not node1 and not node2:
+                return None
+            if not node1:
+                return node2
+            if not node2:
+                return node1
+            node1.val += node2.val
+            node1.left = helper_merge_tree(node1.left, node2.left)
+            node1.right = helper_merge_tree(node1.right, node2.right)
+            return node1
+
+        sum_tree = deepcopy(root1)
+        return helper_merge_tree(sum_tree, root2)

arai60/21-29_Tree_BT_BST/23_617_Merge Two Binary Trees/level_4.py

@@ -0,0 +1,44 @@
+# DFS(非破壊)
+# レビューコメントを反映
+# helper関数をなくした
+class Solution:
+    def mergeTrees(
+        self, root1: Optional[TreeNode], root2: Optional[TreeNode]
+    ) -> Optional[TreeNode]:
+            if not root2:
+                return deepcopy(root1)
+            if not root1:
+                return deepcopy(root2)
+            node = TreeNode(root1.val + root2.val)
+            node.left = self.mergeTrees(root1.left, root2.left)
+            node.right = self.mergeTrees(root1.right, root2.right)
+            return node
+
+# BFS(非破壊)
+# レビューコメントを反映
+class Solution:
+    def mergeTrees(
+        self, root1: Optional[TreeNode], root2: Optional[TreeNode]
+    ) -> Optional[TreeNode]:
+
+        def merge_nodes(node1, node2):
+            if not node2:
+                return deepcopy(node1)
+            if not node1:
+                return deepcopy(node2)
+            new_node = TreeNode(node1.val + node2.val)
+            return new_node
+
+        merged_root = merge_nodes(root1, root2)
+        nodes_queue = deque()
+        if root1 and root2:
+            nodes_queue.append((merged_root, root1, root2))
+        while nodes_queue:
+            merged_node, node1, node2 = nodes_queue.popleft()
+            merged_node.left = merge_nodes(node1.left, node2.left)
+            merged_node.right = merge_nodes(node1.right, node2.right)
+            if node1.left and node2.left:
+                nodes_queue.append((merged_node.left, node1.left, node2.left))
+            if node1.right and node2.right:
+                nodes_queue.append((merged_node.right, node1.right, node2.right))
+        return merged_root