feature: path sum ii

trees/PathSumII.py

@@ -0,0 +1,27 @@
+from typing import Optional, List
+
+from trees.TreeNode import TreeNode
+
+
+# O(n) time || O(max(n, log(n)) space
+def path_sum(self, root: Optional[TreeNode], target_sum: int) -> List[List[int]]:
+    res = []
+
+    def dfs(node, curr_sum, curr_path):
+        if not node:
+            return
+
+        curr_sum += node.val
+        curr_path.append(node.val)
+
+        if not node.left and not node.right and curr_sum == target_sum:
+            res.append(list(curr_path))
+
+        dfs(node.left, curr_sum, curr_path)
+        dfs(node.right, curr_sum, curr_path)
+
+        curr_path.pop()
+
+    dfs(root, 0, [])
+
+    return res

trees/test/test_path_sum.py

@@ -0,0 +1,42 @@
+import unittest
+
+from trees.PathSumII import path_sum
+from trees.TreeNode import TreeNode
+
+
+class MyTestCase(unittest.TestCase):
+    def test_path_sum(self):
+        root = TreeNode(
+            val=5,
+            left=TreeNode(
+                val=4,
+                left=TreeNode(
+                    val=11,
+                    left=TreeNode(7),
+                    right=TreeNode(2)
+                )
+            ),
+            right=TreeNode(
+                val=8,
+                left=TreeNode(13),
+                right=TreeNode(
+                    val=4,
+                    left=TreeNode(5),
+                    right=TreeNode(1)
+                )
+            )
+        )
+        self.assertEqual([[5, 4, 11, 2], [5, 8, 4, 5]], path_sum(self, root, 22))
+
+    def test_path_sum_1(self):
+        root = TreeNode(
+            val=1,
+            left=TreeNode(2),
+            right=TreeNode(3)
+        )
+
+        self.assertEqual([], path_sum(self, root, 0))
+
+
+if __name__ == '__main__':
+    unittest.main()