# EXERCISE 1: Contains

list1 = [1, 2, 'apple', 3, 'banana']
found_3 = False
for value in list1:
    if value == 3:
        found_3 = True
if found_3:
     print 'list1 has a 3'
else:
     print 'list1 has no 3s'

# EXERCISE 2: Counting values

list2 = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5]
ones_count = 0
for value in list2:
    if value == 1:
        ones_count += 1
print 'list2 has', ones_count, 'ones'

# EXERCISE 3: Repeats

list3 = [12, 32, 34, 34, 23, 23, 12, 12]
previous_value = list3[0]
two_in_a_row = False
# Start at the SECOND value in the list:
for value in list3[1:] :
    if value == previous_value:
        two_in_a_row = True
    previous_value = value
if two_in_a_row:
    print 'list3 has 2 in a row'
else:
    print 'list3 does not have 2 in a row'

# EXERCISE 4: Stats

list4 = [12, 32, 33, 35, 23, 23, 12, 12]
total = 0
for value in list4:
     total += value
print 'sum:', total

# EXERCISE 5: Palindromes

list5 = [1, 2, 3, 4, 3, 2, 1]
for index in range(len(list5)):
    if list5[index] % 2 == 1:
        print 'odd value at index',index

# EXERCISE 6: Transitions

list6 = [1, 1, 1, 3, 3, 1, 1, 1, 0, 2, 2, 2]
previous_value = list6[0]
current_run_length = 1
for value in list6[1:] :
    if value == previous_value:
        current_run_length += 1
    else:
        # a run just finished!  Report it, and start counting again
        print 'A run of', current_run_length, previous_value
        current_run_length = 1
    previous_value = value
# There will always be a run left over:
print 'A run of', current_run_length, previous_value