【LeetCode】14. Longest Common Prefix

Write a function to find the longest common prefix string amongst an array of strings.

题意：找出所给几个字符串的相同前缀

思路：用第一个字符串和之后的所有字符串进行对比，标示出相同字符串的超尾指针就行

ps：通过这个题发现自己Python基础好差啊

class Solution(object):
    def longestCommonPrefix(self, strs):
        """
        :type strs: List[str]
        :rtype: str
        """
        if len(strs)==0: return ''
        str = strs[0]
        min = len(str)
        for i in range(1, len(strs)):
            j=0
            tmp = strs[i]
            while j<min and j<len(tmp) and str[j] == tmp[j]:
                j+=1
            if j<min: min = j
        
        return str[:min]

 耗时84ms，排名太靠后了，不能忍

class Solution(object):
    def longestCommonPrefix(self, strs):
        """
        :type strs: List[str]
        :rtype: str
        """
        if len(strs)==0: return ''
        str = strs[0]
        min = len(str)
        for tmp in strs[1:]:
            j=0
            while j<min and j<len(tmp) and str[j]==tmp[j]:
                j+=1
            if j<min: min=j
        
        return str[:min]

 耗时59ms，好了点，但还是不理想

class Solution(object):
    def longestCommonPrefix(self, strs):
        """
        :type strs: List[str]
        :rtype: str
        """
        if len(strs)==0: return ''
        str = strs[0]
        min = len(str)
        for tmp in strs[1:]:
            j = 0
            l = len(tmp)
            while j<min and j<l and str[j]==tmp[j]:
                j+=1
            if j<min: min=j
        
        return str[:min]

把重复计算的min = len(str)保存后，变成了49ms，len()耗时挺长啊，感觉还能继续改

class Solution(object):
    def longestCommonPrefix(self, strs):
        """
        :type strs: List[str]
        :rtype: str
        """
        if len(strs)==0: return ''
        str = strs[0]
        min = len(str)
        for tmp in strs[1:]:
            j = 0
            l = len(tmp)
            while j<min and j<l and str[j]==tmp[j]:
                j+=1
            min=j     #不用判断，j的值肯定小于min，直接更新
        
        return str[:min]

又减了4ms

感觉还能改，但是不知道怎么改了。。。

没办法，

只有这样了。。

！！！！

0ms

char* longestCommonPrefix(char** strs, int strsSize) {
    if(!strsSize) return "";
    char *str=strs[0];
    int i,j;
    for(i=1;i<strsSize;i++){
        j=0;
        while(str[j]&&strs[i][j]&&str[j]==strs[i][j])
            j++;
        str[j]='';
    }
    return str;
}