[Feat] Add some tree implementation

Author: AustinPardosi

112-PathSum.py

@@ -0,0 +1,17 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def hasPathSum(self, root: Optional[TreeNode], targetSum: int) -> bool:
+        if root == None:
+            return False
+
+        if root.val == targetSum and root.left == None and root.right == None:
+            return True
+
+        return self.hasPathSum(root.left, targetSum - root.val) or self.hasPathSum(
+            root.right, targetSum - root.val
+        )

144-BinaryTreePreorderTraversal.py

@@ -0,0 +1,19 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def dfs(self, root: Optional[TreeNode], result: List[int]):
+        if root == None:
+            return result
+        
+        result.append(root.val)
+        self.dfs(root.left, result)
+        return self.dfs(root.right, result)
+
+    def preorderTraversal(self, root: Optional[TreeNode]) -> List[int]:
+        result = []
+        self.dfs(root, result)
+        return result

145-BinaryTreePostorderTraversal.py

@@ -0,0 +1,20 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def dfs(self, root: Optional[TreeNode], result: List[int]):
+        if root == None:
+            return result
+
+        self.dfs(root.left, result)
+        self.dfs(root.right, result)
+        result.append(root.val)
+        return result
+
+    def postorderTraversal(self, root: Optional[TreeNode]) -> List[int]:
+        result = []
+        self.dfs(root, result)
+        return result

94-BinaryTreeInorderTraversal.py

@@ -0,0 +1,20 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def dfs(self, root: Optional[TreeNode], result: List[int]):
+        if root == None:
+            return result
+
+        self.dfs(root.left, result)
+        result.append(root.val)
+        self.dfs(root.right, result)
+        return result
+
+    def inorderTraversal(self, root: Optional[TreeNode]) -> List[int]:
+        result = []
+        self.dfs(root, result)
+        return result