LeetCode之Longest Common Prefix

package leetcode.chenyu.test;
public class LongestCommonPrefix {
  public static void main(String[] args)  {
    String [] ss = {"12345", "3234", "234"};
    String [] ss1 = {"flower", "flow", "flight"};
    String [] ss2 = {"ca", "a"};
    String [] ss3 = {"a", "a"};
    String [] ss4 = {"aa","ab"};
    String [] ss5 = {"abca","aba","aaab"};
    String result =longestCommonPrefix(ss5);
    System.out.printf("result1111:" + result);
  }
  public static boolean isNull(String s) {
    if(s == null || s.length() == 0) {
      return true;
    }
    return false;
  } 
  public  static String longestCommonPrefix(String[] strs) {
    if(strs == null || strs.length ==0) {
      return "";
    }
    int length = strs.length;
    if (length == 1) {
      return strs[0];
    }
    int minLength = Integer.MAX_VALUE;
    int index = 0;
    for (int i = 0; i < strs.length; ++i) {
       if (isNull(strs[i])) {
         return "";
       }
       if (minLength > strs[i].length()) {
         minLength = strs[i].length();
         index = i;
       }
    }
    String result = "";
    for (int i = 1; i <= minLength; ++i) {
       int count = 0;
       for (int j = i; j <= minLength; ++j) {
          String s =  strs[index].substring(count++, j);
          System.out.print("s:" + s + "\t");
          int flag = 0;
          for (int k = 0; k < length; k++) {
            if (k != index) {
              if (!strs[k].contains(s)) {
                break;
              } else {
               flag++;
               System.out.print("flag:" + flag + "\t");
               if (flag == length - 1) {
                 if (result.length() < s.length()) {
                    int num = 0;
                    for (int h = 0; h < length; h++) {
                       if (!strs[h].startsWith(s)) {
                          break;
                       } else {
                         num++;
                       }
                    }
                    if (num == length)
                    result = s;
                 }
                 System.out.println("result:" + result + "\t");
                 break;
               }
              }
             } 
          }
       }
    }
    return result;
  }
}