Recursive function to construct binary tree of size len from Inorder traversal in [ ] and Preorder traversal pre [ ] . Initial values of inStrt and inEnd should be 0 and len - 1. The function doesn 't do any error checking for cases where inorder and preorder do not form a tree
function buildTree ( In , pre , inStrt , inEnd ) { if ( inStrt > inEnd ) return null ;