LeetCode Digest
2 分鐘 閱讀文 (大約 262 個字)

Merge Two Sorted Lists

題目
思路：

  1. 因為要做一個 linked list，可以用 while 在每次迴圈都接一個 node 出來

  2. 先設 while True:，等寫迴圈內容時再來確定 while 可繼續執行的條件

  3. 寫第一 part (如下) 後發現，while 條件需要 l1 and l2

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    if l1.val > l2.val:
        curr.next = l2
        l2 = l2.next
    else:
        curr.next = l1
        l1 = l1.next

  4. post processing: 跳出迴圈後的情形是 l1, l2 其中有一個是 None 或兩個都是 None，此時就把目標 linked list 接上那個不是 None 的即可

Python3 solution:

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def mergeTwoLists(self, l1: Optional[ListNode], l2: Optional[ListNode]) -> Optional[ListNode]:
    dummy_head = ListNode()  # 因為不知道第一個會用 l1 還 l2，所以用 dummy_head
    curr = dummy_head  # 也要有個 curr 可以在每次迴圈中跟著移動
    while l1 and l2:
        if l1.val > l2.val:
            curr.next = l2
            l2 = l2.next
        else:
            curr.next = l1
            l1 = l1.next
        curr = curr.next
    curr.next = l1 or l2  # post processing
    return dummy_head.next

P.S. 有些思路跟 Add Two Numbers 重複，這篇就不多寫了

#
Same Tree
Remove Duplicates from Sorted List

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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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