primes=[]
products=[]

def prime(num):
    if num > 1:
        for i in range(2,num):
            if (num % i) == 0:
                return False
        else:
            primes.append(num)
            return True

for n in range(30,1000):
    if len(primes) >= 20:
        break;
    else:
        prime(n)

for previous, current in zip(primes[::2], primes[1::2]):
    products.append(previous * current)
    
print (products)

# importing the modules
import os
import shutil

# getting the current working directory
src_dir = os.getcwd()

# printing current directory
print(src_dir) 

# copying the files
shutil.copyfile('test.txt', 'test.txt.copy2') #copy src to dst

# printing the list of new files
print(os.listdir())

def max_n(lst, n = 1):
  return sorted(lst, reverse = True)[:n]

max_n([1, 2, 3]) # [3]
max_n([1, 2, 3], 2) # [3, 2]

""" Rock Paper Scissors
----------------------------------------
"""
import random
import os
import re
os.system('cls' if os.name=='nt' else 'clear')
while (1 < 2):
    print "\n"
    print "Rock, Paper, Scissors - Shoot!"
    userChoice = raw_input("Choose your weapon [R]ock], [P]aper, or [S]cissors: ")
    if not re.match("[SsRrPp]", userChoice):
        print "Please choose a letter:"
        print "[R]ock, [S]cissors or [P]aper."
        continue
    // Echo the user's choice
    print "You chose: " + userChoice
    choices = ['R', 'P', 'S']
    opponenetChoice = random.choice(choices)
    print "I chose: " + opponenetChoice
    if opponenetChoice == str.upper(userChoice):
        print "Tie! "
    #if opponenetChoice == str("R") and str.upper(userChoice) == "P"
    elif opponenetChoice == 'R' and userChoice.upper() == 'S':      
        print "Scissors beats rock, I win! "
        continue
    elif opponenetChoice == 'S' and userChoice.upper() == 'P':      
        print "Scissors beats paper! I win! "
        continue
    elif opponenetChoice == 'P' and userChoice.upper() == 'R':      
        print "Paper beat rock, I win! "
        continue
    else:       
        print "You win!"

def counting_sort(arr, exp):
    n = len(arr)
    output = [0] * n
    count = [0] * 10

    for i in range(n):
        index = (arr[i] // exp) % 10
        count[index] += 1

    for i in range(1, 10):
        count[i] += count[i-1]

    i = n - 1
    while i >= 0:
        index = (arr[i] // exp) % 10
        output[count[index] - 1] = arr[i]
        count[index] -= 1
        i -= 1

    for i in range(n):
        arr[i] = output[i]

def radix_sort(arr):
    max_val = max(arr)
    exp = 1
    while max_val // exp > 0:
        counting_sort(arr, exp)
        exp *= 10

if __name__ == "__main__":
    arr = [170, 45, 75, 90, 802, 24, 2, 66]
    print("Original array:", arr)
    radix_sort(arr)
    print("Sorted array:", arr)

# @return a list of strings, [s1, s2]
def letterCombinations(self, digits):
    if '' == digits: return []
    kvmaps = {
        '2': 'abc',
        '3': 'def',
        '4': 'ghi',
        '5': 'jkl',
        '6': 'mno',
        '7': 'pqrs',
        '8': 'tuv',
        '9': 'wxyz'
    }
    return reduce(lambda acc, digit: [x + y for x in acc for y in kvmaps[digit]], digits, [''])