diff --git a/Tree traversal - Preorder b/Tree traversal - Preorder new file mode 100644 index 0000000..fcb5292 --- /dev/null +++ b/Tree traversal - Preorder @@ -0,0 +1,29 @@ +Tree Traversal - Preorder: + +###Iteration### +# Definition for a binary tree node. +# class TreeNode: +# def __init__(self, x): +# self.val = x +# self.left = None +# self.right = None + +class Solution: + def preorderTraversal(self, root: TreeNode) -> List[int]: + res,stack = [],[root] + while stack: + cur = stack.pop() + if cur: + res.append(cur.val) + stack.append(cur.right) + stack.append(cur.left) + return res + +###Recursion###: + +class Solution: + def preorderTraversal(self, root: TreeNode) -> List[int]: + res =[] + if root: + res += [root.val]+self.preorderTraversal(root.left)+ self.preorderTraversal(root.right) + return res