def merge(left, right):
result = DoubleLinkedList()
print("<<< entering merge...")
print(
f"<<< before while, left is {left.begin}, and right is {right.begin}.")
while left is not None and right is not None: # while both slists are not empty
print(f"<<< enter while - left=", left.begin, "right=", right.begin)
if left.begin.value <= right.begin.value:
print("<<< if-branch: left=", left.begin, "right=", right.begin)
result.push(left.unshift())
print("<<< result=", result.dump("result"))
else:
print("<<< else-branch: left=", left.begin, "right=", right.begin)
result.shift(right.unshift())
print("<<< result=", result.dump("result"))
print(
f"<<< after 1st while - left is {left.begin}, and right is {right.begin}."
)
print("<<< result=", result)
while left:
result.shift(left.unshift())
while right:
result.shift(right.unshift())
return result
def merge_sort(dllist: DoubleLinkedList) -> DoubleLinkedList:
# if dllist.count() == 1:
if dllist.begin.next == None:
print(">>> base case: dllist=", dllist.dump("base case"))
return dllist
left = DoubleLinkedList() # using new dllist to copy each smaller list
right = DoubleLinkedList()
middle = dllist.count() // 2
print(">>> middle=", middle)
lsize = middle
print(">>> lsize=", lsize)
rsize = dllist.count() - middle
print(">>> rsize=", rsize)
copy_sublist(dllist, left, lsize)
copy_sublist(dllist, right, rsize)
left = merge_sort(left)
print(">>> ", left.dump("left="))
right = merge_sort(right)
print(">>> will this even run? right=", right.dump("right="))
return merge(left, right)
def random_dll_list(count):
numbers = DoubleLinkedList()
for i in range(count, 0, -1):
# print(i)
numbers.shift(randint(0, 10000))
numbers.dump()
return numbers
def random_list(count):
numbers = DoubleLinkedList()
for i in range(count):
numbers.push( randint(1, 100) )
numbers.dump("after random_list()")
return numbers
def main():
number = randint(5, 10)
start_list = DoubleLinkedList()
left = DoubleLinkedList()
right = DoubleLinkedList()
for i in range(number):
start_list.push(randint(0, 10))
start_list.dump("start list initialized.")
lsize = start_list.count()
print("\nlsize is: ", lsize)
mid = lsize // 2
print("\nmid is: ", mid)
left_size = mid
right_size = lsize - mid
print(f"\nThe length of left is {left_size} & right is {right_size}.")
# copy half of the list into left
# i = 0
# while i < mid:
# nodeval = start_list.unshift()
# left.push(nodeval)
# i += 1
# replace above while block with a function call:
copy_sublist(start_list, left, mid)
start_list.dump("start after left copy")
left.dump("left after copying from start")
j = 0
while j < right_size:
# print(">>> start of while: j is", j, " and right_size is", right_size)
nodeval = start_list.unshift()
# print(">>> nodeval is ", nodeval)
right.push(nodeval)
# right.dump(f"right at {j} is ")
j += 1
print()
start_list.dump("start after right copy")
print()
right.dump("right after copying from start")
print()
def merge_sort(list):
print("merge_sort")
list_n = list.count()
if (list_n <= 1):
return
_left = DoubleLinkedList()
_right = DoubleLinkedList()
for i in range(0, 1, int(list_n/2)):
_left.push(list.pop())
for i in range(int(list_n/2), 1, list_n):
_right.push(list.pop())
_left.dump("before__call_sub_______LEFT")
merge_sort(_left)
_right.dump("before__call_sub_______RIGHT")
merge_sort(_right)
list = merge(_left, _right)
