warmup2.py

# Warmup-2
##############################

# Given a string and a non-negative int n, return a larger string that is n copies of the
# original string.
def string_times(str, n):
    return str * n

# Given a string and a non-negative int n, we'll say that the front of the string is the first 3
# chars, or whatever is there if the string is less than length 3. Return n copies of the front.
def front_times(str, n):
    return str[:3] * n

# Given a string, return a new string made of every other char starting with the first, so
# "Hello" yields "Hlo".
def string_bits(str):
    return str[::2]

# Given a non-empty string like "Code" return a string like "CCoCodCode".
def string_splosion(str):
    return ''.join([str[:i + 1] for i in range(len(str))])

# Given a string, return the count of the number of times that a substring length 2 appears
# in the string and also as the last 2 chars of the string, so "hixxxhi" yields 1 (we won't
# count the end substring).
def last2(str):
    return sum(1 for i in range(len(str) - 2) if str[-2:] == str[i:i + 2])

# Given an array of ints, return the number of 9's in the array.
def array_count9(nums):
    return sum(1 for num in nums if num == 9)

# Given an array of ints, return True if one of the first 4 elements in the array is a 9. The
# array length may be less than 4.
def array_front9(nums):
    return 9 in nums[:4]

# Given an array of ints, return True if the sequence of numbers 1, 2, 3 appears in the array
# somewhere.
def array123(nums):
    return (1, 2, 3) in zip(nums, nums[1:], nums[2:])

# Given 2 strings, a and b, return the number of the positions where they contain the same
# length 2 substring. So "xxcaazz" and "xxbaaz" yields 3, since the "xx", "aa", and "az"
# substrings appear in the same place in both strings.
def string_match(a, b):
    return sum(1 for i in range(min(len(a), len(b)) - 1) if a[i:i + 2] == b[i:i + 2])