from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
dummy = ListNode(0)
curr_node = dummy
while l1 and l2:
if l1.val > l2.val:
curr_node.next = l2
l2 = l2.next
else:
curr_node.next = l1
l1 = l1.next
curr_node = curr_node.next
if l1 is None:
curr_node.next = l2
else:
curr_node.next = l1
return dummy.next
if __name__ == '__main__':
PrintListNode(Solution().mergeTwoLists(MakeListNodes([1, 3, 4]), MakeListNodes([1, 2, 4])))
PrintListNode(Solution().mergeTwoLists(None, None))
from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def swapPairs(self, head: ListNode) -> ListNode:
if head is None or head.next is None:
return head
node_list = list()
while head:
node_list.append(head)
head = head.next
# 分为奇列表和偶列表,末尾节点补None为了方便
odd_list = node_list[::2] + [None]
even_list = node_list[1::2] + [None]
# 头为偶列表的第一个节点
# 重排的顺序为： even[0] -> odd[0] -> even[1] -> odd[1] -> ....
result = even_list[0]
for i in range(len(even_list) - 1):
even_list[i].next = odd_list[i]
odd_list[i].next = even_list[i + 1] if even_list[i + 1] else (odd_list[i + 1] if odd_list[i + 1] else None)
return result
if __name__ == '__main__':
PrintListNode(Solution().swapPairs(MakeListNodes([1, 2, 3, 4])))
PrintListNode(Solution().swapPairs(MakeListNodes([1, 2, 3])))
from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def rotateRight(self, head: ListNode, k: int) -> ListNode:
if not head:
return head
# 先整个循环链表
length = 1
start = end = head
while end.next:
length += 1
end = end.next
end.next = start
# 计算要移动的步数
# 需要做一下转换
right_step = length - k % length
for _ in range(right_step):
start = start.next
end = end.next
end.next = None
return start
if __name__ == '__main__':
PrintListNode(Solution().rotateRight(MakeListNodes([0, 1, 2]), 4))
PrintListNode(Solution().rotateRight(MakeListNodes([1, 2, 3, 4, 5]), 2))
# return head
def reorderList(self, head: ListNode):
"""
Do not return anything, modify head in-place instead.
"""
if not head:
return
fast = slow = head
while fast and fast.next:
fast = fast.next.next
slow = slow.next
curr_node, prev_node = slow, None
while curr_node:
curr_node.next, prev_node, curr_node = prev_node, curr_node, curr_node.next
odd_head = head
even_head = prev_node
while even_head.next:
odd_head.next, odd_head = even_head, odd_head.next
even_head.next, even_head = odd_head, even_head.next
return head
if __name__ == '__main__':
PrintListNode(Solution().reorderList(None))
PrintListNode(Solution().reorderList(MakeListNodes([1, 2, 3, 4])))
PrintListNode(Solution().reorderList(MakeListNodes([1, 2, 3, 4, 5])))
def mergeKLists(self, lists: List[ListNode]) -> ListNode:
from queue import PriorityQueue
node_queue = PriorityQueue()
for index, node in enumerate(lists):
node_queue.put((node.val, index, node)) if node else ...
dummy = ListNode(0)
curr_node = dummy
while not node_queue.empty():
_, index, tmp_node = node_queue.get() # 使用优先队列
curr_node.next = tmp_node
curr_node = curr_node.next
node_queue.put((tmp_node.next.val, index,
tmp_node.next)) if tmp_node.next else ...
return dummy.next
if __name__ == '__main__':
PrintListNode(Solution().mergeKLists([
MakeListNodes([1, 4, 5]),
MakeListNodes([1, 3, 4]),
MakeListNodes([2, 6])
]))
PrintListNode(Solution().mergeKLists([None]))
class Solution:
def sortedListToBST(self, head: ListNode) -> TreeNode:
if not head:
return None
elif head.next is None: # head的下一个节点为None，则它为叶子节点
return TreeNode(head.val)
fast_node = slow_node = pre_node = head # pre_node用来记录中间那个节点的前一个节点
while fast_node and fast_node.next:
pre_node = slow_node
fast_node, slow_node = fast_node.next.next, slow_node.next
pre_node.next = None # 将中间节点父节点的子节点截断
root = TreeNode(slow_node.val) # root节点为中间节点
root.left = self.sortedListToBST(head) # 递归左节点
root.right = self.sortedListToBST(slow_node.next) # 递归右节点
return root
if __name__ == '__main__':
# res = Solution().sortedListToBST(None)
# res = Solution().sortedListToBST(MakeListNodes([-10, -3, 0, 5, 9]))
res = Solution().sortedListToBST(
MakeListNodes([
-93, -89, -85, -76, -56, -53, -20, -10, 20, 28, 41, 50, 66, 70, 87,
88, 91, 94
]))
pass
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def sortList(self, head: ListNode) -> ListNode:
node_list = list()
while head:
node_list.append(head)
head = head.next
node_list.sort(key=lambda x: x.val)
length = len(node_list)
node_list.append(None)
for index in range(length):
node_list[index].next = node_list[index + 1]
return node_list[0]
if __name__ == '__main__':
PrintListNode(Solution().sortList(None))
PrintListNode(Solution().sortList(MakeListNodes([4, 2, 1, 3])))
# return head
#
# node_set.add(head)
# head = head.next
#
# return None
def detectCycle(self, head):
"""
:type head: ListNode
:rtype: ListNode
"""
# python2 中set的实现还不是散列表的形式，效率上比dict慢
node_dict = dict()
while head:
if head in node_dict:
return head
node_dict.update({head: 1})
head = head.next
return None
if __name__ == '__main__':
node = MakeListNodes([1, 2, 3, 4, 5, 6, 7])
node.next.next.next.next.next = node.next
print(Solution().detectCycle(node).val)
#
# [206] Reverse Linked List
#
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def reverseList(self, head: ListNode) -> ListNode:
if not head:
return
curr_node, prev_node = head, None
while curr_node:
# curr_node.next, curr_node, prev_node = prev_node, curr_node.next, curr_node # 这种方式比较耗时
tmp = curr_node.next
curr_node.next = prev_node
prev_node = curr_node
curr_node = tmp
return prev_node
if __name__ == '__main__':
PrintListNode(Solution().reverseList(head=MakeListNodes([1, 3, 4])))
next_larger_list.append(0)
curr_val = head.val
while stack and stack[-1][0] < curr_val:
top_node = stack.pop()
next_larger_list[top_node[1]] = curr_val
stack.append((curr_val, index))
index += 1
head = head.next
return next_larger_list
if __name__ == '__main__':
print(Solution().nextLargerNodes(MakeListNodes([7, 2, 6, 6, 9, 4, 3])))
print(Solution().nextLargerNodes(MakeListNodes([9, 7, 6, 7, 6, 9])))
print(Solution().nextLargerNodes(MakeListNodes([2, 5, 5])))
print(Solution().nextLargerNodes(MakeListNodes([2, 1, 5])))
print(Solution().nextLargerNodes(MakeListNodes([2, 7, 4, 3, 5])))
print(Solution().nextLargerNodes(MakeListNodes([1, 7, 5, 1, 9, 2, 5, 1])))
# print("Use recursion")
# print(Solution().nextLargerNodes_recursion(MakeListNodes([7, 2, 6, 6, 9, 4, 3])))
# print(Solution().nextLargerNodes_recursion(MakeListNodes([9, 7, 6, 7, 6, 9])))
# print(Solution().nextLargerNodes_recursion(MakeListNodes([2, 5, 5])))
# print(Solution().nextLargerNodes_recursion(MakeListNodes([2, 1, 5])))
# print(Solution().nextLargerNodes_recursion(MakeListNodes([2, 7, 4, 3, 5])))
# print(Solution().nextLargerNodes_recursion(MakeListNodes([1, 7, 5, 1, 9, 2, 5, 1])))
import json
# self.next = None
from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def partition(self, head: ListNode, x: int) -> ListNode:
if not head:
return head
less_part = list()
great_part = list()
while head:
if head.val < x:
less_part.append(head)
else:
great_part.append(head)
head = head.next
part_list = less_part + great_part + [None]
for i in range(len(part_list) - 1):
part_list[i].next = part_list[i + 1]
return part_list[0]
if __name__ == '__main__':
PrintListNode(Solution().partition(MakeListNodes([1, 4, 3, 2, 5, 2]), 3))
return head
# 奇、偶节点
odd_node = head
even_node = head.next
# 偶数头，最后连接用
even_head = even_node
# 偶数节点为末尾节点，所以判断其为None为结束标志
while even_node:
# 如果偶数节点存在，则奇数节点的next为偶数节点的next
odd_node.next = even_node.next
# 如果偶数节点的next(也就是下一个奇数节点)存在
# 则奇数、偶数节点进行更新
if even_node.next:
odd_node = odd_node.next
even_node.next = odd_node.next
even_node = even_node.next
# 奇数节点的末尾与偶数节点的头部连接
odd_node.next = even_head
return head
if __name__ == '__main__':
PrintListNode(Solution().oddEvenList(MakeListNodes([1, 2, 3, 4, 5])))
PrintListNode(Solution().oddEvenList(MakeListNodes([2, 1, 3, 5, 6, 4, 7])))
else:
if insert_node is not None:
node_list.append(insert_node)
insert_node = None
head = head.next
else:
if insert_node is not None:
node_list.append(insert_node)
return len(node_list)
def numComponents_2(self, head: ListNode, G: List[int]) -> int:
prev_node = None
component_num = 0
G_set = set(G) # 性能提升的关键啊！
while head:
if head.val in G_set:
if prev_node is None or prev_node.val not in G_set:
component_num += 1
prev_node = head
head = head.next
return component_num
if __name__ == '__main__':
# print(Solution().numComponents(head=MakeListNodes([0, 1, 2, 3]), G=[0, 1, 3]))
print(Solution().numComponents_2(head=MakeListNodes([0, 1, 2, 3]),
G=[0, 1, 3]))
# @lc app=leetcode id=876 lang=python3
#
# [876] Middle of the Linked List
#
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def middleNode(self, head: ListNode) -> ListNode:
if not head:
return
fast, slow = head, head
while fast and fast.next:
fast = fast.next.next
slow = slow.next
return slow
if __name__ == '__main__':
PrintListNode(Solution().middleNode(MakeListNodes([1])))
PrintListNode(Solution().middleNode(MakeListNodes([1, 2, 3, 4])))
PrintListNode(Solution().middleNode(MakeListNodes([1, 2, 3, 4, 5])))
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def deleteDuplicates(self, head: ListNode) -> ListNode:
dummy = ListNode(0)
curr_node = dummy
tmp_list = set()
while head:
if head.val in tmp_list:
head = head.next
else:
tmp_list.add(head.val)
curr_node.next = head
curr_node = curr_node.next
curr_node.next = None
return dummy.next
if __name__ == '__main__':
PrintListNode(Solution().deleteDuplicates(MakeListNodes([1, 1, 2])))
PrintListNode(Solution().deleteDuplicates(MakeListNodes([1, 1, 2, 3, 3])))
for part in part_list:
if len(part) == k:
part.reverse()
else:
part.append(None)
# 将各组元素解开，最后一个元素如果不为None，则将其next元素指向None，防止构成循环链表
part_list_new = list()
for part in part_list:
part_list_new.extend(part)
if part_list_new and part_list_new[-1] is not None:
part_list_new[-1].next = None
# 链接前后各个元素
for index in range(len(part_list_new)):
if part_list_new[index] is not None and index + 1 < len(
part_list_new):
part_list_new[index].next = part_list_new[index + 1]
return part_list_new[0] if part_list_new else None
if __name__ == '__main__':
PrintListNode(Solution().reverseKGroup(MakeListNodes([1, 2]), k=2))
PrintListNode(Solution().reverseKGroup(MakeListNodes([1, 2, 3, 4, 5]),
k=1))
PrintListNode(Solution().reverseKGroup(MakeListNodes([1, 2, 3, 4, 5]),
k=2))
PrintListNode(Solution().reverseKGroup(MakeListNodes([1, 2, 3, 4, 5]),
k=3))
# @lc app=leetcode id=234 lang=python3
#
# [234] Palindrome Linked List
#
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def isPalindrome(self, head: ListNode) -> bool:
node_list = list()
while head:
node_list.append(head.val)
head = head.next
return all([v1 == v2 for v1, v2 in zip(node_list, node_list[::-1])])
if __name__ == '__main__':
print(Solution().isPalindrome(MakeListNodes([1])))
print(Solution().isPalindrome(None))
print(Solution().isPalindrome(MakeListNodes([1, 0, 0])))
print(Solution().isPalindrome(MakeListNodes([1])))
print(Solution().isPalindrome(MakeListNodes([1, 2])))
print(Solution().isPalindrome(MakeListNodes([1, 2, 2, 1])))
result = list()
for i in range(k):
# 1、如果有余数
# 前面节点的个数 = 平均个数 + 1
part_len = average + 1 if div else average
div = div - 1 if div else div
# 添加对应块的节点
result.append(root_head)
if root_head is None:
continue
for j in range(part_len - 1):
root_head = root_head.next
# 各块结束后，将末尾的节点的下一跳指向None
root_pre = root_head
root_head = root_head.next
root_pre.next = None
return result
if __name__ == '__main__':
for part in Solution().splitListToParts(root=MakeListNodes(
[1, 2, 3, 4, 5, 6, 7, 8, 9]),
k=10):
PrintListNode(part)
#
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def deleteDuplicates(self, head: ListNode) -> ListNode:
if not head or not head.next:
return head
# 如果头部前两个数字相同，则去除从头开始的重复数字
if head.val == head.next.val:
while (head.next is not None) and (head.val == head.next.val):
head = head.next
return self.deleteDuplicates(head.next)
else:
# 如果头部前两个数字不相同，则头部的下一个节点为递归后的结果
head.next = self.deleteDuplicates(head.next)
return head
if __name__ == '__main__':
PrintListNode(Solution().deleteDuplicates(
MakeListNodes([1, 2, 2, 3, 3, 4, 5])))
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
from LeetCode.Python.BaseListNode import MakeListNodes, PrintListNode, ListNode
class Solution:
def insertionSortList(self, head: ListNode) -> ListNode:
node_list = list()
while head:
node_list.append((head.val, head))
head = head.next
node_list.sort(key=lambda x: x[0])
length = len(node_list)
node_list.append((0, None))
for index in range(length):
node_list[index][1].next = node_list[index + 1][1]
return node_list[0][1]
if __name__ == '__main__':
PrintListNode(Solution().insertionSortList(None))
PrintListNode(Solution().insertionSortList(MakeListNodes([4, 2, 1, 3])))