---
title: 14.Longest Common Prefix
tags: Leetcode,2021
---
# 【LeetCode】 14. Longest Common Prefix
## Description
>Write a function to find the longest common prefix string amongst an array of strings.

>If there is no common prefix, return an empty string "".
## Example

Example 1:

Input: strs = ["flower","flow","flight"]
Output: "fl"
Example 2:

Input: strs = ["dog","racecar","car"]
Output: ""

>Explanation: There is no common prefix among the input strings.

## Constraints:

1 <= strs.length <= 200
0 <= strs[i].length <= 200
strs[i] consists of only lower-case English letters.

## Solution

public class Solution {
    public string LongestCommonPrefix(string[] strs) {
        if (strs.Length == 0 || strs == null) return "";
            string pre = strs[0];
            int i = 1;
            while (i < strs.Length)
            {
                while (strs[i].IndexOf(pre)!=0)
                {
                    
                    pre = pre.Substring(0, pre.Length - 1);
                }
                
                i++;
            }
            return pre;
    }
}