14. Longest Common Prefix （计算一组字符串最长公共前缀）

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

public class Solution {
    public String longestCommonPrefix(String[] strs) {
        if(strs.length==0)
        return "";
        StringBuilder sb = new StringBuilder();
		int minLen = Integer.MAX_VALUE;
		char ch;
		for (String str : strs)
			if (str.length() < minLen)
				minLen = str.length();
		for(int i=0;i