[Problem 145] Binary Tree Postorder Traversal

Author: minaShaker2p

src/easy/BinaryTreePostorderTraversal145.kt

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+package easy
+
+/**
+ * Given the root of a binary tree, return the postorder traversal of its nodes' values.
+
+
+
+Example 1:
+
+
+Input: root = [1,null,2,3]
+Output: [3,2,1]
+Example 2:
+
+Input: root = []
+Output: []
+Example 3:
+
+Input: root = [1]
+Output: [1]
+
+
+Constraints:
+
+The number of the nodes in the tree is in the range [0, 100].
+-100 <= Node.val <= 100
+
+
+Follow up: Recursive solution is trivial, could you do it iteratively?
+ */
+
+fun postorderTraversal(root: TreeNode?): List<Int> {
+
+}