2problems completed

pathsum-II.py

@@ -0,0 +1,23 @@
+class Solution:
+    def pathSum(self, root: Optional[TreeNode], targetSum: int) -> List[List[int]]:
+        self.result=[]
+        self.helper(root,targetSum,0,[])
+        return self.result
+
+
+
+    def helper(self, root, targetSum,currsum,path):
+
+        if root==None:
+            return
+
+        currsum=currsum+root.val
+        path.append(root.val)
+        if root.left==None and root.right==None:
+            if currsum==targetSum:
+                self.result.append(list(path))
+
+        self.helper(root.left,targetSum,currsum,path)
+        self.helper(root.right,targetSum,currsum,path)
+
+        path.pop()

symmetric tree.py

@@ -0,0 +1,37 @@
+# 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 isSymmetric(self, root: Optional[TreeNode]) -> bool:
+
+        if root is None:
+            return False
+
+        queue=[]
+        queue.append(root.left)
+        queue.append(root.right)
+
+        while queue:
+            left=queue.pop(0)
+            right=queue.pop(0)
+
+            if left is None and right is None:
+                continue
+            if left is None or right is None:
+                return False
+            if left.val!=right.val:
+                return False
+            queue.append(left.left)
+            queue.append(right.right)
+            queue.append(left.right)
+            queue.append(right.left)
+
+
+        return True
+
+
+
+