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enhance swapping code in link #1660

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Merged
merged 6 commits into from
Jan 14, 2020
Merged

enhance swapping code in link #1660

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ec56dec
enhance swapping code in link
lanzhiwang Jan 6, 2020
bbfbf7a
heapify do not recursive
lanzhiwang Jan 6, 2020
2051ecb
fix
lanzhiwang Jan 6, 2020
d0c81ed
fix identifier and add test
lanzhiwang Jan 12, 2020
8a09815
typing.Any and LinkedList instead of Linkedlist
lanzhiwang Jan 14, 2020
517fc1b
typing.Any and LinkedList instead of Linkedlist
lanzhiwang Jan 14, 2020
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69 changes: 15 additions & 54 deletions data_structures/linked_list/swap_nodes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -11,8 +11,9 @@ def __init__(self):
def print_list(self):
temp = self.head
while temp is not None:
print(temp.data)
print(temp.data, end=' ')
temp = temp.next
print()

# adding nodes
def push(self, new_data):
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Needs type hints and more pythonic condition checking

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Do we want to limit the data type? Currently this can be used with many different data types and I consider that a feature, not a bug.

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Then let's be consistent by using typing.Any

Expand All @@ -21,72 +22,32 @@ def push(self, new_data):
self.head = new_node

# swapping nodes
def swapNodes(self, d1, d2):
prevD1 = None
prevD2 = None
if d1 == d2:
def swap_nodes(self, node_data_1, node_data_2):
if node_data_1 == node_data_2:
return
else:
# find d1
D1 = self.head
while D1 is not None and D1.data != d1:
prevD1 = D1
D1 = D1.next
# find d2
D2 = self.head
while D2 is not None and D2.data != d2:
prevD2 = D2
D2 = D2.next
if D1 is None and D2 is None:
return
# if D1 is head
if prevD1 is not None:
prevD1.next = D2
else:
self.head = D2
# if D2 is head
if prevD2 is not None:
prevD2.next = D1
else:
self.head = D1
temp = D1.next
D1.next = D2.next
D2.next = temp

def swapNodes2(self, d1, d2):
if d1 == d2:
return
else:
D1 = self.head
while D1 is not None and D1.data != d1:
D1 = D1.next
node_1 = self.head
while node_1 is not None and node_1.data != node_data_1:
node_1 = node_1.next

D2 = self.head
while D2 is not None and D2.data != d2:
D2 = D2.next
node_2 = self.head
while node_2 is not None and node_2.data != node_data_2:
node_2 = node_2.next

if D1 is None or D2 is None:
if node_1 is None or node_2 is None:
return

D1.data, D2.data = D2.data, D1.data
node_1.data, node_2.data = node_2.data, node_1.data

# swapping code ends here


if __name__ == "__main__":
list = Linkedlist()
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list is the name of a Python builtin so it should not be used as a variable name.

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@onlinejudge95 onlinejudge95 Jan 13, 2020 •
edited by cclauss
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Also according to PEP8 should the class names be LinkedList instead of Linkedlist

list.push(5)
list.push(4)
list.push(3)
list.push(2)
list.push(1)
for i in range(5, 0, -1):
list.push(i)

list.print_list()

list.swapNodes(1, 4)
print("After swapping")
list.print_list()

list.swapNodes2(1, 4)
list.swap_nodes(1, 4)
print("After swapping")
list.print_list()