4/31 每日一題

 Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

 

Example 1:

Input: haystack = "sadbutsad", needle = "sad"
Output: 0
Explanation: "sad" occurs at index 0 and 6.
The first occurrence is at index 0, so we return 0.

Example 2:

Input: haystack = "leetcode", needle = "leeto"
Output: -1
Explanation: "leeto" did not occur in "leetcode", so we return -1.

 

Constraints:

• 1 <= haystack.length, needle.length <= 104
• haystack and needle consist of only lowercase English characters.

import re

haystack = "sadbutsad"

needle = "sad"

if re.search(needle,haystack):

    for i in re.finditer(needle,haystack):

        #finditer是一個可迭代資料,可以找出「每次」匹配到的索引

        print(i.span())  #回傳一組tuple

if re.search(needle,haystack):

    print(re.search(needle,haystack).start())

    #start()回傳開始的索引,但他只會找到第一個

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終端機

PS C:\Users\K\OneDrive\桌面\AUTOKI> & C:/Users/K/AppData/Local/Programs/Python/Python311/python.exe c:/Users/K/OneDrive/桌面/AUTOKI/tes.py (0, 3) (6, 9) 0 PS C:\Users\K\OneDrive\桌面\AUTOKI>