Leetcode简单：14. 最长公共前缀

题目：最长公共前缀

• 题号：14
• 难度：简单
• https://leetcode-cn.com/problems/longest-common-prefix/

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 “”。

示例 1:

输入：strs = ["flower","flow","flight"]
输出："fl"

示例 2:

输入：strs = ["dog","racecar","car"]
输出：""
解释：输入不存在公共前缀。

提示:

• 1 <= strs.length <= 200
• 0 <= strs[i].length <= 200
• strs[i] 仅由小写英文字母组成

---

实现

C# 语言

public class Solution 
{
    public string LongestCommonPrefix(string[] strs) 
    {
        if (strs.Length == 0)
            return string.Empty;

        string result = strs[0];
        for (int i = 1; i < strs.Length; i++)
        {
            result = Prefix(result, strs[i]);
            if (string.IsNullOrEmpty(result))
                break;
        }
        return result;        
    }
    
    public string Prefix(string str1, string str2)
    {
        int len1 = str1.Length;
        int len2 = str2.Length;
        int len = Math.Min(len1, len2);
        int i = 0;
        for (; i < len; i++)
        {
            if (str1[i] != str2[i])
                break;
        }
        return i == 0 ? string.Empty : str1.Substring(0, i);
    }   
}

Python 语言

class Solution(object):
    def longestCommonPrefix(self, strs):
        """
        :type strs: List[str]
        :rtype: str
        """
        if len(strs) == 0:
            return ""
        result = strs[0]
        for i in range(len(strs)):
            result = self.Prefix(result, strs[i])
            if result == "":
                break
        return result
    
    def Prefix(self, str1, str2):
        len1, len2 = len(str1), len(str2)
        i = 0
        while i < min(len1, len2):
            if str1[i] != str2[i]:
                break
            i += 1
        return "" if i == 0 else str1[0:i]