# Answers to StringList Test 1.5

# Problem #1

def StrStrip(s):
    while len(s) > 0:
        if s[0] == ' ':
            s = s[1:]
        else:
            break
    while len(s) > 0:
        if s[-1] == ' ':
            s = s[:-1]
        else:
            break
    return s

# Problem #2

def StrSplit(s,c):
    answer = []
    original_s = s
    pos = s.find(c)
    while pos >= 0:
        answer.append(s[:pos])
        s = s[pos+1:]
        pos = s.find(c)
    if len(s) > 0:
        answer.append(s)
    elif original_s[-1] == c:
        answer.append('')
    return answer

# Problem 3
def IsInt(s):
    s = StrStrip(s)
    if len(s) == 0:
        return False
    if s[0] == '+' or s[0] == '-':
        s = s[1:]
        if len(s) == 0:
            return False
    for c in s:
        if "0123456789".find(c) < 0:
            return False
    return True

# Problem 4
def Mode(L):
    best_so_far = L[0]
    best_so_far_dups = 1
    current = L[0]
    dups = 1
    for i in range(1,len(L)):
        num = L[i]
        if num == current:
            dups += 1
            if dups > best_so_far_dups:
                best_so_far_dups = dups
                best_so_far = current
        else:
            current = num
            dups = 1
    return best_so_far