Re: [閒聊] 每日LeetCode

[JerryChungYC (JerryChung)]

https://leetcode.com/problems/first-unique-character-in-a-string

387. First Unique Character in a String

給一個字串s，找到第一個不重複的字元回傳其索引，不存在則回傳-1

Example 1:
Input: s = "leetcode"
Output: 0

Example 2:
Input: s = "loveleetcode"
Outpue: 2

Example 3:
Input: s = "aabb"
Output: -1

思路：
用for迴圈找出只出現一次的字元

Python3 code:
----------------------------------------------------
class Solution:
    def firstUniqChar(self, s: str) -> int:
        for i, w in enumerate(s):
            if s.count(w) == 1:
                return i
        return -1
----------------------------------------------------
簡單 快速 4448ms
https://i.imgur.com/ZvmHhKo.png

思路：
用Counter找出所有字元出現的次數，再回傳value第一個為1的

Python3 code:
----------------------------------------------------
class Solution:
    def firstUniqChar(self, s: str) -> int:
        counter = Counter(s)
        if 1 not in counter.values(): return -1
        for k, v in counter.items():
            if v == 1:
                return s.find(k)
----------------------------------------------------
https://i.imgur.com/1Wq3c52.png

上週連寫了5天 結果六日都沒寫 哈
就不會動態規劃((

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※ 編輯: JerryChungYC (125.227.251.109 臺灣), 02/05/2024 08:56:04
→ JIWP: 大師
推 PyTorch: 大師
推 wu10200512: 這不是哈希表ㄇ
→ JerryChungYC: 那就自己建 counter = {} :(
→ JerryChungYC: counter = defaultdict(int)
→ JerryChungYC: for i in s:
→ JerryChungYC:     counter[i] += 1