def sum_lists_tt(ll1, ll2):
''' sums two linked lists
ex:
ll1 = 7 -> 1 -> 6 (617)
ll2 = 5 -> 9 -> 2 (295)
result = 617 + 295 = 912 = 2 -> 1 -> 9
'''
result = Linked_List()
carry = 0
if len(ll1) > len(ll2):
big = ll1.head
small = ll2.head
else:
big = ll2.head
small = ll1.head
while big:
if small:
num = big.data + small.data + carry
small = small.next
else:
num = big.data + carry
if num < 10: # no double digit, no carry
carry = 0
else:
carry = 1
num %= 10 #get digit in one's place
big = big.next
result.add_back(num)
return result
def partition(ll, val):
''' changes linked list ll to have all values < val on left of all values >= val '''
if ll.head is None: # no nodes
return False
if ll.head.next is None: # 1 node
return False
# create 2 linked lists that contain values >= or < val
gte_ll = Linked_List()
lt_ll = Linked_List()
cur = ll.head
while cur:
if cur.data >= val:
gte_ll.add_front(cur.data)
else:
lt_ll.add_front(cur.data)
cur = cur.next
# combine linked lists
if lt_ll.tail is not None:
lt_ll.tail.next = gte_ll.head
ll.head = lt_ll.head
return True
def forward_sum_lists(ll1, ll2):
''' sums two linked lists
ex:
ll1 = 6 -> 1 -> 7 (617)
ll2 = 2 -> 9 -> 5 (295)
result = 617 + 295 = 912
output = 9 -> 1 -> 2
'''
result = Linked_List()
carry = 0
last = None
if len(ll1) > len(ll2):
big = ll1
small = ll2
else:
big = ll2
small = ll1
# 0 pad the small linked list to make same # nodes
for _ in range ( len(big) - len(small) ):
small.add_front(0)
big = big.head
small = small.head
while big:
val = big.data + small.data
#no need to add a carry
if val < 10 and last is not None:
result.add_back(last)
last = val
elif last is not None: #val >= 10
result.add_back(last + 1) #add the carry
last = val % 10
else:
last = val
big = big.next
small = small.next
return result
if cur.data >= val:
gte_ll.add_front(cur.data)
else:
lt_ll.add_front(cur.data)
cur = cur.next
# combine linked lists
if lt_ll.tail is not None:
lt_ll.tail.next = gte_ll.head
ll.head = lt_ll.head
return True
if __name__ == "__main__":
print '---------Test 1-------------'
ll = Linked_List()
ll.add_front(1)
ll.add_back(2)
ll.add_back(4)
ll.add_back(9)
ll.add_back(5)
ll.add_back(3)
ll.add_back(6)
ll.add_back(2)
ll.add_back(2)
print ll
print "calling partition, val = 4"
print partition(ll, 4)
print ll
print '---------Test 2-------------'
for _ in range(k):
if fast is None:
return None # out of bounds
fast = fast.next
while fast:
slow = slow.next
fast = fast.next
return slow
if __name__ == "__main__":
print '---------Test 1-------------'
ll = Linked_List()
ll.add_front(1)
ll.add_back(2)
ll.add_back(3)
ll.add_back(4)
ll.add_back(5)
ll.add_back(6)
print ll
print "calling kth to last, k = 0 (invalid)"
print kth_to_last(0, ll)
print "calling kth to last, k = len(ll) (first)"
print kth_to_last(len(ll), ll)
print "calling kth to last, k = 1 (last)"
print kth_to_last(1, ll)
print "calling kth to last, k = 2 (second to last)"
print kth_to_last(2, ll)
while cur:
d[cur] = True
cur = cur.next
cur = ll2.head
while cur:
if cur in d:
return cur
cur = cur.next
return None
if __name__ == "__main__":
print "--------------Test 1--------------"
ll1 = Linked_List()
ll2 = Linked_List()
a = Node('a')
b = Node('b')
c = Node('c')
d = Node('d')
e = Node('e')
ll1.head = a
a.next = b
b.next = c
c.next = e
ll1.tail = e
# a -> b -> c - > e
def test_alt_func(self):
for [nodes, expected] in self.data:
ll = Linked_List()
ll.gen(*nodes)
self.assertEqual(alt_palindrome(ll), expected)
last = val % 10
else:
last = val
big = big.next
small = small.next
return result
if __name__ == "__main__":
print '---------Test 1-------------'
ll1 = Linked_List()
ll1.add_back(7)
ll1.add_back(1)
ll1.add_back(6)
ll2 = Linked_List()
ll2.add_back(5)
ll2.add_back(9)
ll2.add_back(2)
print ll1
print ll2
print "calling sum_lists()"
print sum_lists(ll1, ll2)
print '---------Test 2-------------'
print 'One empty list'
ll1 = Linked_List()
if ll.head is None:
return
slow = fast = ll.head
while slow:
while fast.next:
if slow.data == fast.next.data:
fast.next = fast.next.next
else:
fast = fast.next
slow = fast = slow.next
if __name__ == "__main__":
print '---------Test 1-------------'
ll = Linked_List()
ll.add_front(4)
ll.add_back(5)
ll.add_back(6)
ll.add_back(6)
ll.add_back(7)
ll.add_back(6)
print ll
print "calling remove dups"
remove_dups(ll)
print ll
print '---------Test 2-------------'
ll = Linked_List()
ll.add_front(4)
ll.add_back(5)
ll.add_back(6)