[LeetCode]#14 Longest Common Prefix

 1 class Solution:
 2     # @param {string[]} strs
 3     # @return {string}
 4     def longestCommonPrefix(self, strs):
 5         #in thie problem, we need to find the longest common prefix
 6         #i set the result string <str>longest to store the common prefix
 7         #first I let longest = strs[0], and to compare each strs[i], do "-" operation
 8         #eg:strs=[‘she‘, "shanghai", "super"]
 9         #round0: longest = "she", len=3
10         #round1: "she" != "shanghai"[:3], so cut the last one in longest
11         #        longest = "sh", len=2
12         #        "sh" == "shanghai"[:2],ok ,the next
13         #round2: "sh" != "shper"[:2], cut the last one in longest
14         #        longest = "s", len=1
15         #        "s" == super[:1], ok, return longest = "s"
16         length = len(strs)
17         if length == 0:
18             return ""
19         elif length == 1:
20             return strs[0]
21         else:
22             longest = strs[0]
23             for i in range(1, length):
24                 if strs[i] == "":
25                     return ""
26                 else:
27                     while longest != strs[i][:len(longest)]:
28                         len_longest = len(longest)
29                         longest = longest[:len_longest - 1]
30                         if longest == "":
31                             return ""
32             return longest