# Answers to Lists and String Exercises

# 1a. ========================================================
def LFindWhile(someList,someElement):
    i = 0
    while i < len(someList):
        if someList[i] == someElement:
            return i
        i += 1
    return -1

# print LFindWhile([3, 4, "hi", -2], "hi")
# print LFindWhile([3, 4, "hi", -2], "HI")

# 1b. ========================================================
def LFindNoWhile(someList,someElement):
    if someElement in someList:
        return someList.index(someElement)
    return -1

# print LFindNoWhile([3, 4, "hi", -2], "hi")
# print LFindNoWhile([3, 4, "hi", -2], "HI")

# 2. ==========================================================
def CountSomeChars(s):
    littleHalf = "abcdefghijklm"
    half = littleHalf + littleHalf.upper()
    count = 0
    for c in s:
        if c in half:
            count += 1
    return count

# print CountSomeChars('Hi there')

# 3. =============================================================
def HarmonicSum(n):
    total = 0
    for i in range(1,1001):
        total += 1.0/i
    return total

# print '%.3f' % HarmonicSum(1000)

# There are special, built-in number formatting commands that we can make use
#   of (though not covered in class)
# To find out, go to the usual French Python page:
#    http://rgruet.free.fr/PQR27/PQR2.7.html
#   and search for "string formatting with the % operator"

# 4. ==============================================================
def Select23(someList):
    result = []
    for n in someList:
        if n%2 == 0 or n%3 == 0:
            result.append(n)
    return result

# print Select23([5,0,12,9,7,4])
# print Select23([5,7,1])

# 5a. =============================================================
def RemoveNegs(L):
    result = []
    for n in L:
        if n >= 0:
            result.append(n)
    return result

# L = [2, -3, 0, -5, 12]
# print RemoveNegs(L)
# print L

# 5b. =============================================================
def RemoveNegsInPlace(L):
    i = 0
    while i < len(L):
        if L[i] < 0:
            del L[i]
        else:
            i += 1
            
# L = [2, -3, 0, -5, 12]
# print RemoveNegsInPlace(L)
# print L

# Challenge =========================================================
def WordList(someString):
    # remove all commas and periods
    someString = someString.replace(',','')
    someString = someString.replace('.','')
    return someString.split()

# print WordList('  Now, Scotty, use the dilithium crystals.')

# Hard Challenge ====================================================
def MySplit(someString,separators):
    insideWord = False
    words = []
    currentWord = ''
    
    for c in someString:
        if c in separators:
            if insideWord:
                words.append(currentWord)
                currentWord = ''
                insideWord = False
        else:
            insideWord = True
            currentWord += c

    # if there's still a currentWord building up...
    if insideWord:
        words.append(currentWord)

    return words

# print MySplit(" Hi there... Mr. Bleeper,  "," ,.e")
# print MySplit("What's up?"," ,!")