LeetCode Digest
1 分鐘 閱讀文 (大約 219 個字)

Reverse Linked List

題目
思路

  1. 因為是 linked list，我們可以使用 curr 當指標，沿著 linked list 的頭往後走，一邊改變 curr.next 的指向，而過程中必須對前一個和下一個都有所掌握，因為 curr 必須指向前一個，然後它本身必須換到下一個
  2. 所以我們會有三個變數：previous, curr, next
  3. 當 curr 是 head 時，previous 會是 None，這兩個可以先設定好。目標是一直改變 curr 的指向，讓 curr 一直走到 linked list 盡頭，變成 None 為止，所以 while 條件就是 當有 curr 的時候就做

Python 3 solution:

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# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]:
    previous = None
    curr = head
    while curr:
        next = curr.next
        curr.next = previous
        previous = curr
        curr = next
    return previous
#
142. Linked List Cycle II
Isomorphic Strings

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android array authentication binary search binary search tree binary tree bit manipulation breadth-first search database depth-first search distributed system django docker dokku dynamic programming graph greedy hash table heap heroku java jwt linked list matrix mysql paas package management pipenv postgresql python recursion shortest path simulation sliding window sorting stack string tree two pointers

最新文章

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標籤

android 2
array 5
authentication 1
binary search 1
binary search tree 1
binary tree 6
bit manipulation 2
breadth-first search 5
database 2
depth-first search 9
distributed system 1
django 1
docker 3
dokku 1
dynamic programming 4
graph 2
greedy 1
hash table 6
heap 1
heroku 1
java 1
jwt 1
linked list 5
matrix 1
mysql 1
paas 1
package management 1
pipenv 1
postgresql 1
python 9
recursion 11
shortest path 1
simulation 1
sliding window 1
sorting 1
stack 2
string 4
tree 7
two pointers 3

最新文章

彙整

標籤

android 2
array 5
authentication 1
binary search 1
binary search tree 1
binary tree 6
bit manipulation 2
breadth-first search 5
database 2
depth-first search 9
distributed system 1
django 1
docker 3
dokku 1
dynamic programming 4
graph 2
greedy 1
hash table 6
heap 1
heroku 1
java 1
jwt 1
linked list 5
matrix 1
mysql 1
paas 1
package management 1
pipenv 1
postgresql 1
python 9
recursion 11
shortest path 1
simulation 1
sliding window 1
sorting 1
stack 2
string 4
tree 7
two pointers 3
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