Interview Code Written for Stripe (9/1/2016) by Arani Bhattacharyay

tracker.py

import unittest

def next_server_number(input):
    if len(input) == 0:
        return 1
    output = 1
    for value in input:
        if value == output:
            output += 1
    return output
   

class TestNextServer(unittest.TestCase):
    
    def test_blank(self):
        self.assertEquals(next_server_number([]), 1)
    
    def test_basic(self):
        self.assertEquals(next_server_number([5, 4, 1, 2]), 3)
        self.assertEquals(next_server_number([1, 2, 3, 4, 5]), 6)
        self.assertEquals(next_server_number([5, 4, 3, 2]), 1)
        self.assertEquals(next_server_number([1, 2, 3, 4, 6]), 5)
        
if __name__ == '__main__':
    unittest.main()
    
    
def is_number(s):
    try:
        int(s)
        return True
    except ValueError:
        return False

   
class Tracker 
    def __init__(self):
        self.map = {}
    
    def allocate(input):
        if self.map.has_key(input):
            val = next_server_number()
            self.map[input].append(val)
            return input + val
        self.map[input] = [1]
        return input + 1
        
    def next_server_number(input):
        if len(input) == 0:
            return 1
        output = 1
        for value in input:
            if value == output:
                output += 1
        return output
   
    def deallocate(input)
        i = 0
        val = 0
        name = ""
        for char in input:
            if (is_number(char)):
                val = int(input[i:])
                name = input[:i]
            i += 1
        self.map[name].remove(val)
        if len(self.map[name]) == 0:
            del self.map[name] 
        return None