leetcode —— 字串相關（28、344）

0. 字串搜尋

• 28. Implement strStr()
  

  class Solution:
      def strStr(self, haystack, needle):
          """
          :type haystack: str
          :type needle: str
          :rtype: int
          """
          # return haystack.find(needle)
          if not needle:
              return 0
          n_haystack, n_needle = len(haystack), len(needle)
          for i in range(len(haystack)):
              if haystack[i:i+n_needle] == needle:
                  return i
          return -1
  

  使用 python 內建庫函式：

  class Solution:
      def strStr(self, haystack, needle):
          return haystack.find(needle)
  

1. 翻轉字串

• 344. Reverse String
  

  class Solution:
      def reverseString(self, s):
          """
          :type s: str
          :rtype: str
          """
          arr = list(s)
          i, j = 0, len(arr)-1
          while i < j:
              arr[i], arr[j] = arr[j], arr[i]
              i += 1
              j -= 1
          return ''.join(arr)