【最长公共前缀】Longest Common Prefix

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

解法：以strs[0]作为基准，依次查看其子序列是否是公共前缀

public class Solution {
    public String longestCommonPrefix(String[] strs) {
        String prefix = "";
        String str = "";
        int len = strs.length;
        if(len == 0) return prefix;
        if(len == 1) return strs[0];
        
        prefix = strs[0];
        boolean flag = false;
        for(int i=prefix.length(); i>=0 && !flag; i--){
            str = prefix.substring(0, i);
            int j=1;
            for(; j<len; j++){
                if(strs[j].startsWith(str) == false) break;
            }
            if(j == len) flag = true;
        }
        return str;
    }
}