leetcode第14题——*Longest Common Prefix

题目

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

思路

寻找字符串数组中所有字符串的最长公共前缀，注意是所有字符串的公共前缀，比如数组['hello', 'hell', 'he']的最长公共前缀为'he'。显然如果存在空字符串则公共前缀为空字符串。可以先将第一个字符串存在结果变量prefix中，然后，从第二个字符串开始找跟prefix相同的字符并更新。

代码

Python

class Solution(object):    def longestCommonPrefix(self, strs):        """        :type strs: List[str]        :rtype: str        """        strNum = len(strs)        if (strs == None or strNum == 0):            return ''        prefix = strs[0]                for i in xrange(1, strNum):            if (prefix == '' or strs[i] == ''):                return ''            comLen = min(len(prefix), len(strs[i]))            j = 0            while (j < comLen and prefix[j] == strs[i][j]):                j += 1            prefix = prefix[0:j]        return prefix

Java

public class Solution {    public String longestCommonPrefix(String[] strs) {        int strNum = strs.length;if (strs == null || strNum == 0) return "";String prefix = strs[0];int i,j,len;for(i = 1;i < strNum;i++){if (prefix == "" || strs[i] == "") return "";len = Math.min(prefix.length(),strs[i].length());for(j = 0; j<len && prefix.charAt(j)==strs[i].charAt(j); j++);prefix = prefix.substring(0,j);}return prefix;    }}