def q2_a(l):
    '''Return True if list l does *not* contain adjacent elements with the same
    value, and False otherwise.  For example, no_duplicates([0,1,2,3])
    returns True, and  no_duplicates([0,1,2,3,3]) returns False.'''

    print "running q2_a(%s)" % (str(l))
    i = 0
    while i+1 < len(l):
        print "top: i=%d \tl=%s" % (i,l)
        if l[i] == l[i+1]:
            return False
        else:
            return True
        i += 1

def q2_b(l):
    print "running q2_b(%s)" % (str(l))
    i = 0
    while i+1 < len(l) and l[i] == l[i+1]:
        print "1st: i=%d \tl=%s" % (i,l)
        return False
    while i+1 < len(l) and l[i] != l[i+1]:
        print "2nd: i=%d \tl=%s" % (i,l)
        i += 1
    return True

def q2_c(l):
    print "running q2_c(%s)" % (str(l))
    if len(l) < 2:
        return True
    for i in range(0,len(l)-1):
        if l[i] == l[i+1]:
            return False
        elif l[i] != l[i+1]:
            if i == len(l) - 2:
                return True

def q2_d(l):
    print "running q2_d(%s)" % (str(l))
    x = ()
    for item in l:
        if item == x:
            return False
        else:
            x = item
    return True

def q2_d_fixed(l):
    print "running q2_d_fixed(%s)" % (str(l))
    if not l:
        return True
    else:
        # we know there is at least one element
        # so, this won't cause an error
        x = l[0]
        for item in l[1:]:
           if item == x:
               return False
           else:
               x = item
        return True

def q2_e(l):
    print "running q2_e(%s)" % (str(l))
    index = 0
    a = l[index]
    b = l[index+1]
    while a != b and index < len(l) - 1:
        index = index + 1
    if a == b:
       return False
    else:
       return True

def q2_e_almost_fixed(l):
    print "running q2_e_almost_fixed(%s)" % (str(l))
    index = 0
    a = l[index]
    b = l[index+1]
    while a != b and index < len(l) - 2:
        index = index + 1
        a = l[index]
        b = l[index+1]
    if a == b:
       return False
    else:
       return True


def q2_e_fixed(l):
    print "running q2_e_fixed(%s)" % (str(l))
    index = 0
    while index < len(l) - 2 and l[index] != l[index+1]:    
        index = index + 1
    if len(l) < 2:
        return True
    else:
       if l[index] == l[index+1]:
          return False
       else:
          return True

if __name__ == '__main__':

   # q2_a
   # Which of these will be wrong???
   #    Index out of range error?
   #    Infinite loop?
   #    Incorrect answer?
   #For each, how many times will it go through the loop? 
   #x = q2_a([0,1,2,3,4])
   #print x, "sb", True 

   #x = q2_a([0,0,2,3,4])
   #print x, "sb", False

   #x = q2_a([0,2,3,3])
   #print x, "sb", False

   #q2_b

   #x = q2_b([2,2,2,2])
   #print x, "sb", False

   #x = q2_b([0,2,3,3])
   #print x, "sb", False

   # q2_c 

   #x = q2_c([0,1,2,3,4])
   #print x, "sb", True 

   #x = q2_c([0,0,2,3,4])
   #print x, "sb", False

   #x = q2_c([0,2,3,3])
   #print x, "sb", False

   #x = q2_c([])
   #print x, "sb", True


   #x = q2_d([10,11,12,13])
   #print x, "sb", True 

   #x = q2_d([0,0,2,3,4])
   #print x, "sb", False

   #x = q2_d([0,2,3,3])
   #print x, "sb", False

   #x = q2_d([])
   #print x, "sb", True

   #x = q2_d([(),3,4,5])
   #print x, "sb", True

#  q2_d_fixed
   #x = q2_d_fixed([10,11,12,13])
   #print x, "sb", True 

   #x = q2_d_fixed([0,2,3,3])
   #print x, "sb", False

   #x = q2_d_fixed([33])
   #print x, "sb", True

   # q2_e solves a different task!
   #
   #x = q2_e([0,1,2,3,4])
   #print x, "sb", True 

   #x = q2_e([0,0,2,3,4])
   #print x, "sb", False

   #x = q2_e([0,2,3,3])
   #print x, "sb", False

   #x = q2_e([])
   #print x, "sb", True

   #x = q2_e_almost_fixed([0,1,2,3,4])
   #print x, "sb", True 

   #x = q2_e_almost_fixed([0,0,2,3,4])
   #print x, "sb", False

   #x = q2_e_almost_fixed([0,2,3,3])
   #print x, "sb", False

   #x = q2_e_almost_fixed([])
   #print x, "sb", True

   #x = q2_e_fixed([0,1,2,3,4])
   #print x, "sb", True 

   #x = q2_e_fixed([0,0,2,3,4])
   #print x, "sb", False

   #x = q2_e_fixed([0,2,3,3])
   #print x, "sb", False

   #x = q2_e_fixed([])
   #print x, "sb", True