https://www.hackerrank.com/challenges/contacts/problem

contacts.py

# https://www.hackerrank.com/challenges/contacts/problem
# We're going to make our own Contacts application! The application must perform two types of operations:
#   1. add name, where name is a string denoting a contact name. This must store name as a new contact in 
#      the application.
#   2. find partial, where partial is a string denoting a partial name to search the application for. It 
#      must count the number of contacts starting with partial and print the count on a new line.
# Given n sequential add and find operations, perform each operation in order.

# INPUT FORMAT:
# The first line contains a single integer, n, denoting the number of operations to perform. 
# Each line i of the n subsequent lines contains an operation in one of the two forms defined above.

from collections import defaultdict

contacts = []
partials = [defaultdict(lambda: 0) for _ in range(22)]

for _ in range(int(input())):
    q = input().split()
    if q[0] == 'add':
        for i in range(1, len(q[1]) + 1):
            partials[i][q[1][:i]] += 1
    else:
        print(partials[len(q[1])][q[1]])