LeetCode Digest
1 分鐘 閱讀文 (大約 112 個字)

Binary Number with Alternating Bits

題目

  1. 先想到的是有沒有辦法透過 bitwise operation 來判斷，發現無法
  2. 看相鄰位置有沒有一樣的，最直覺就是用字串來判斷 => 可以利用 Python 的 built-in function bin 來把數字轉為 binary 字串

Python3 solution:

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def hasAlternatingBits(self, n: int) -> bool:
    b_str = bin(n)[2:]  # 去掉前面的 '0b'
    for i in range(len(b_str) - 1):
        if b_str[i] == b_str[i + 1]:
            return False
    return True
LeetCode Digest
1 分鐘 閱讀文 (大約 177 個字)

Single Number

題目

  1. 因為只能用常數的額外空間，且 array 裡的數字除了目標之外都會有兩個，所以朝 bitwise operation 的方向想
  2. 把 array 裡所有數字接連做 bitwise operation，假如有兩個一樣的數字，他們就會抵銷變為 0，即使不是連著做也一樣，所以最後的結果就是那個落單的數字
    • 可以想像所有數字都用二進位表示由上而下列在一起做計算，不管他們位置怎麼換結果都會一樣 (偶數個 1 會互相抵銷)

Python3 solution:

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def singleNumber(self, nums: List[int]) -> int:
    r = 0
    for i in nums:
        r ^= i
    return r

分類

標籤雲

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

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

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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