Write a function to find the longest common prefix string amongst an array of strings.

import java.util.Scanner;
import java.util.logging.Logger;

import org.omg.PortableInterceptor.SYSTEM_EXCEPTION;

public class Solution {
public static String longestCommonPrefix(String[] strs) {
if (strs.length == 0) return "";

for (int j = 0; j < strs[0].length(); ++j){ // 纵向扫描
for (int i = 1; i < strs.length; ++i){
if (j == strs[i].length() ||strs[i].charAt(j) != strs[0].charAt(j))
return strs[0].substring(0, j);
}
}
return strs[0];
}
public static void main(String[] args) {
String strs[] = new String[]{"abcdefg","abcef","abcdeabcg"};
System.out.println(longestCommonPrefix(strs));
}
}