Added constructBinaryTree solution

Author: nhistory

construct-binary-tree-from-preorder-and-inorder-traversal/nhistory.js

@@ -0,0 +1,17 @@
+var buildTree = function (preorder, inorder) {
+  // Edge case: if either preorder or inorder is empty, return null
+  if (!preorder.length || !inorder.length) return null;
+
+  // The first element in preorder is the root of the tree
+  // Find the index of the root in the inorder array
+  const root = new TreeNode(preorder[0]);
+  const mid = inorder.indexOf(root.val);
+
+  root.left = buildTree(preorder.slice(1, mid + 1), inorder.slice(0, mid));
+  root.right = buildTree(preorder.slice(mid + 1), inorder.slice(mid + 1));
+
+  return root;
+};
+
+// TC: O(n)
+// SC: O(n)