Created
July 10, 2019 16:53
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0092 Reverse Linked List II
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# Definition for singly-linked list. | |
# class ListNode: | |
# def __init__(self, x): | |
# self.val = x | |
# self.next = None | |
class Solution: | |
def reverseBetween(self, head: ListNode, m: int, n: int) -> ListNode: | |
if m == n: return head | |
st = [] | |
left, node = None, head | |
if m != 1: | |
for i in range(1, m - 1): | |
node = node.next | |
left = node | |
node = node.next # position m | |
for i in range(m, n + 1): | |
st.append(node) | |
node = node.next | |
l1, l2 = st.pop(), None | |
if m == 1: | |
head = l1 | |
else: | |
left.next = l1 | |
while st: | |
l2 = st.pop() | |
l1.next = l2 | |
l1 = l2 | |
l1.next = node | |
return head | |
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