2 questions :\n\n1. Range sum of BST\n2. Given a list of Contacts, where each contact consists of a contact ID and a list of email IDs. Output a unique list of contacts by removing duplicates. Two contacts are considered to be the same, if they share at least one email ID.\n\teg :-  U1 - abc@gmail.com, def@gmail.com\n\t\t\t U2 - def@gmail.com, xyz@hotmail.com\n\t\t\t U3 - xyz@hotmail.com, tuv@gmail.com\n\t\t\t U4 - ab@gmail.com, bc@gmail.com\n\t\n\tans - ((U1, U2, U3), (U4))\n\t

2 questions :\n\n1. Range sum of BST\n2. Given a list of Contacts, where each contact consists of a contact ID and a list of email IDs. Output a unique list of 