Using index in Inorder traversal , construct left and right subtress
node . left = buildUtil ( In , post , inStrt , iIndex - 1 , postStrt , postStrt - inStrt + iIndex - 1 ) ; node . right = buildUtil ( In , post , iIndex + 1 , inEnd , postEnd - inEnd + iIndex , postEnd - 1 ) ; return node ; }