给一个单词一个字典，每次删除单词里任一个字母直到剩下一个字母，形成一个序列，比如office->offce->ofce->ofc->oc->c。问是否字典里存在一个这种序列

 package checkDictExistSequence;

 import java.util.*;

 public class Solution {

     HashSet<String> dict = new HashSet<String>();

     public String check(String[] arr, String word) {

         for (String str : arr)

             dict.add(str);

         if (checkSeq(new StringBuffer(word))) return "true";

         return "false";

     }

     public boolean checkSeq(StringBuffer sb) {

         if (sb.length() == 1) return true;

         for (int i=0; i<=sb.length()-1; i++) {

             char cur = sb.charAt(i);

             sb.deleteCharAt(i);

             if (dict.contains(sb.toString())) {

                 if (checkSeq(sb)) return true;

             }

             sb.insert(i, cur);

         }

         return false;

     }

     /**

      * @param args

      */

     public static void main(String[] args) {

         // TODO Auto-generated method stub

         Solution sol = new Solution();

         System.out.println(sol.check(new String[]{"offce", "ofce", "ofc", "oc", "c"}, "office"));

     }

 }