Binary Tree Minimum Path Sum

Author: anantkaushik

Apple/Problem#580.py

@@ -0,0 +1,28 @@
+"""
+Given a binary tree, find a minimum path sum from root to a leaf.
+For example, the minimum path in this tree is [10, 5, 1, -1], which has sum 15.
+  10
+ /  \
+5    5
+ \     \
+   2    1
+       /
+     -1
+"""
+class Solution:
+    def minPathSum(self, root: TreeNode) -> int:
+        self.ans = float('inf')
+        
+        def helper(root, cur_sum=0):
+            if not root:
+                self.ans = min(self.ans, cur_sum)
+                return 0
+            
+            cur_sum += root.val
+            l = helper(root.left, cur_sum)
+            r = helper(root.right, cur_sum)
+            cur_sum -= root.val
+            
+        helper(root)
+        
+        return self.ans