- Binary Tree Maximum Path Sum DaleStudy#287

Author: ayosecu

binary-tree-maximum-path-sum/ayosecu.py

@@ -0,0 +1,54 @@
+from typing import Optional
+
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+class Solution:
+    """
+        - Time Complexity: O(n), n = The number of nodes
+        - Space Complexity: O(H), H = The height of Tree
+    """
+    def maxPathSum(self, root: Optional[TreeNode]) -> int:
+        self.max_sum = float("-inf")
+
+        def dfs(node):
+            if not node:
+                return 0
+
+            # Find max sum from the left and right children (more than 0)
+            l_sum = max(dfs(node.left), 0)
+            r_sum = max(dfs(node.right), 0)
+
+            # Calculate current sum and update max_sum
+            current_sum = node.val + l_sum + r_sum
+            self.max_sum = max(self.max_sum, current_sum)
+
+            # Return larger path
+            return node.val + max(l_sum, r_sum)
+
+        dfs(root)
+
+        return self.max_sum
+    
+def do_test():
+    sol = Solution()
+
+    root1 = TreeNode(1)
+    root1.left = TreeNode(2)
+    root1.right = TreeNode(3)
+    e1 = 6
+    r1 = sol.maxPathSum(root1)
+    print(f"TC 1 is Passed!" if r1 == e1 else f"TC 1 is Failed! - Expected: {e1}, Result: {r1}")
+
+    root2 = TreeNode(-10)
+    root2.left = TreeNode(9)
+    root2.right = TreeNode(20)
+    root2.right.left = TreeNode(15)
+    root2.right.right = TreeNode(7)
+    e2 = 42
+    r2 = sol.maxPathSum(root2)
+    print(f"TC 2 is Passed!" if r2 == e2 else f"TC 2 is Failed! - Expected: {e2}, Result: {r2}")
+
+do_test()