Add solution #106

Author: JoshCrozier

README.md

@@ -111,6 +111,7 @@
 103|[Binary Tree Zigzag Level Order Traversal](./0103-binary-tree-zigzag-level-order-traversal.js)|Medium|
 104|[Maximum Depth of Binary Tree](./0104-maximum-depth-of-binary-tree.js)|Easy|
 105|[Construct Binary Tree from Preorder and Inorder Traversal](./0105-construct-binary-tree-from-preorder-and-inorder-traversal.js)|Medium|
+106|[Construct Binary Tree from Inorder and Postorder Traversal](./0106-construct-binary-tree-from-inorder-and-postorder-traversal.js)|Medium|
 108|[Convert Sorted Array to Binary Search Tree](./0108-convert-sorted-array-to-binary-search-tree.js)|Easy|
 110|[Balanced Binary Tree](./0110-balanced-binary-tree.js)|Easy|
 111|[Minimum Depth of Binary Tree](./0111-minimum-depth-of-binary-tree.js)|Easy|

solutions/0106-construct-binary-tree-from-inorder-and-postorder-traversal.js

@@ -0,0 +1,35 @@
+/**
+ * 106. Construct Binary Tree from Inorder and Postorder Traversal
+ * https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/
+ * Difficulty: Medium
+ *
+ * Given two integer arrays inorder and postorder where inorder is the inorder traversal of a
+ * binary tree and postorder is the postorder traversal of the same tree, construct and return
+ * the binary tree.
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {number[]} inorder
+ * @param {number[]} postorder
+ * @return {TreeNode}
+ */
+var buildTree = function(inorder, postorder) {
+  if (inorder.length === 0) return null;
+
+  const root = postorder[postorder.length - 1];
+  const index = inorder.indexOf(root);
+
+  return {
+    val: root,
+    left: buildTree(inorder.slice(0, index), postorder.slice(0, index)),
+    right: buildTree(inorder.slice(index + 1), postorder.slice(index, -1))
+  };
+};