2021-01-11 Python百日打卡学习自【夸可编程】

题目

编写一个函数来查找字符串数组中的最长公共前缀。如果不存在公共前缀，返回空字符串 ''
例子

["flower","flow","flight"] -> 'fl'
["dog","racecar","car"] -> ''
假设

输入的字符串一定不为None或空串
输入的字符串中的字符仅为小写英文字母
tips

找出前两个字符串的最长公共前缀
找1中最长公共前缀和下一个串的最长公共前缀
继续找上一个最长公共前缀和下一个串最长公共前缀

网站答案

答案

解法:

    def longestCommonPrefix(strs: List[str])
        if not strs:
            return ""
        
        prefix, count = strs[0], len(strs)
        for i in range(1, count):
            prefix = self.lcp(prefix, strs[i])
            if not prefix:
                break
        
        return prefix

    def lcp(str1, str2):
        length, index = min(len(str1), len(str2)), 0
        while index < length and str1[index] == str2[index]:
            index += 1
        return str1[:index]

性能
时间复杂度O(mn)
空间复杂度O(1)

我的答案

from functools import reduce


def findCommonPrefixOfTwoString(s1, s2):
    n = min(len(s1), len(s2))
    i = 0
    while i < n:
        if s1[i] == s2[i]:
            i += 1
        else:
            break
    return s1[:i]

# print(findCommonPrefixOfTwoString('123', '456'))

def longestCommonPrefix(strs):
    return reduce(findCommonPrefixOfTwoString, strs)

s1 = ["flower","flow","flight"]
s2 = ["dog","racecar","car"]

print(longestCommonPrefix(s1))
print(longestCommonPrefix(s2))