# LeetCode 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"

## Constraints

0 <= 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) {
int index = 0;
String first = strs[0];
outerloop:
for (int i = 0; i < first.length(); i++) {
for (String x : strs) {
if (i < x.length()) {
if (first.charAt(i) == x.charAt(i)) {
index = i;
} else {
index = i - 1;
break outerloop;
}
} else {
index = i - 1;
break outerloop;
}
}
}
if (first.length() != 0) {
return first.substring(0, index + 1);
} else {
return "";
}
}
return "";
}
}

## Feedback

// 풀이 1

public String longestCommonPrefix(String[] strs) {
if (strs.length == 0) return "";
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;
}
// 풀이 2

public String longestCommonPrefix(String[] strs) {
if (strs == null || strs.length == 0) return "";
for (int i = 0; i < strs[0].length() ; i++){
char c = strs[0].charAt(i);
for (int j = 1; j < strs.length; j ++) {
if (i == strs[j].length() || strs[j].charAt(i) != c)
return strs[0].substring(0, i);
}
}
return strs[0];
}

Source