Word Break II leetcode java

本文轉載自查看原文 2014-07-30 02:49 3052 leetcode每題整理

題目：

Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word.

Return all such possible sentences.

For example, given
s = "catsanddog",
dict = ["cat", "cats", "and", "sand", "dog"].

A solution is ["cats and dog", "cat sand dog"].

題解：

這道題不僅僅是看是不是wordbreak，還需要在此基礎上把所有word break的結果保存。

為了把所有可能性都保存，那么就使用DFS方法來解決。DFS主要就是跳的層次不容易看出，我下面就以字符串leetcode字典le l et eet code作為例子畫了一張圖，大概講解了如何遞回和返回，這樣更加有助於理解。

代碼如下：

1      public boolean wordBreakcheck(String s, Set<String> dict) {
2          if(s== null || s.length()==0)
3              return true;
4          boolean[] res = new boolean[s.length()+1];
5         res[0] = true;
6          for( int i=0;i<s.length();i++){
7             StringBuilder str = new StringBuilder(s.substring(0,i+1));
8              for( int j=0;j<=i;j++){
9                  if(res[j] && dict.contains(str.toString())){
10                     res[i+1] = true;
11                      break;
12                 }
13                 str.deleteCharAt(0);
14             }
15         }
16          return res[s.length()];
17     }
18
19      public ArrayList<String> wordBreak(String s, Set<String> dict) {
20         ArrayList<String> res = new ArrayList<String>();
21          if(s== null || s.length()==0)
22              return res;
23          if(wordBreakcheck(s,dict))
24             helper(s,dict,0,"",res);
25          return res;
26     }
27      private void helper(String s, Set<String> dict, int start, String item, ArrayList<String> res){
28          if(start>=s.length()){
29             res.add(item);
30              return;
31         }
32
33         StringBuilder str = new StringBuilder();
34          for( int i=start;i<s.length();i++){
35             str.append(s.charAt(i));
36              if(dict.contains(str.toString())){
37                 String newItem = new String();
38                  if(item.length()>0)
39                     newItem = item + " " + str.toString();
40                  else
41                     newItem = str.toString();
42                 helper(s,dict,i+1,newItem,res);
43             }
44         }
45     }

Reference: http://blog.csdn.net/linhuanmars/article/details/22452163

免責聲明！

本站轉載的文章為個人學習借鑒使用，本站對版權不負任何法律責任。如果侵犯了您的隱私權益，請聯系本站郵箱yoyou2525@163.com刪除。

猜您在找 Word Ladder II leetcode java [leetcode]Word Break leetcode -- Word Break [LeetCode] Word Break 解題思路 LeetCode:Word Ladder I II [leetcode]Word Ladder II @ Python Combination Sum II leetcode java Word Search leetcode java Word Ladder leetcode java [LeetCode] 291. Word Pattern II 詞語模式之二