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# 0014. Longest Common Prefix

<https://leetcode.com/problems/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 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.

## ac

```java
class Solution {
    public String longestCommonPrefix(String[] strs) {
        // edge cases
        if (strs == null || strs.length == 0) return "";

        // pick first one, compare each char with the rest 
        String comp = strs[0];
        for (int i = 0; i < comp.length(); i++) {
            for (int j = 1; j < strs.length; j++) {
                if (strs[j].length() <= i || strs[j].charAt(i) != comp.charAt(i)) {
                    return comp.substring(0, i);
                }
            }
        }

        return comp;
    }
}
```