【leetcode】Longest Common Prefix

題目簡述：

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

解題思路：

class Solution:
    # @return a string
    def longestCommonPrefix(self, strs):
        if strs == []:
            return ''

        minl = 99999
        for i in strs:
            if len(i) < minl:
                minl = len(i)

        pre = ''
        for i in range(minl):
            t = strs[0][i]
            for j in range(1,len(strs)):
                if t != strs[j][i]:
                    return pre
            pre += t
        return pre