feat: finish path sum in python

Author: bujosa

alternative/easy/path_sum.py

@@ -0,0 +1,39 @@
+class TreeNode:
+ def __init__(self, x):
+ self.val = x
+ self.left = None
+ self.right = None
+
+def has_path_sum(root, sum):
+ if root is None:
+ return False
+
+ stack = [(root, sum)]
+
+ while stack:
+ node, curr_sum = stack.pop()
+ if node.left is None and node.right is None and node.val == curr_sum:
+ return True
+ if node.left is not None:
+ stack.append((node.left, curr_sum - node.val))
+ if node.right is not None:
+ stack.append((node.right, curr_sum - node.val))
+ return False
+
+# Test case
+t1 = TreeNode(5)
+t2 = TreeNode(4)
+t3 = TreeNode(8)
+t4 = TreeNode(11)
+t6 = TreeNode(4)
+t7 = TreeNode(7)
+t8 = TreeNode(2)
+t9 = TreeNode(1)
+t6.right = t9
+t4.right = t8
+t4.left = t7
+t3.right = t6
+t2.left = t4
+t1.right = t3
+t1.left = t2
+assert has_path_sum(t1, 22) == True