---
# System prepended metadata

title: LeetCode 14. Longest Common Prefix

---

# LeetCode 14. Longest Common Prefix

## 題目
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 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.
```
## 解題思維
抓第一個字串，跟下一個字串做字元比對
先比對出相同子字串的位置，否則做字串切割，直到找出相同的子字串

## 圖解

![](https://i.imgur.com/tt140TB.png)



## Java

```
 public String longestCommonPrefix(String[] strs) {
        String prefix = strs[0];
    for (int i = 1; i < strs.length; i++)
        while (strs[i].indexOf(prefix) != 0) {
            prefix = prefix.substring(0, prefix.length() - 1);
            if (prefix.isEmpty()) return "";
        }        
    return prefix;
    }
```