[LeetCode] 140. Word Break II java

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題目：

Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, add spaces in s to construct a sentence where each word is a valid dictionary word. You may assume the dictionary does not contain duplicate words.

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"].

題意及分析：給出一個字串和一個字典，求能用字典裡的單詞將字串分割的所有可能。使用深度遍曆的方法，每次判斷字串是否以字典中的單詞為開頭，如果是開頭，繼續判斷剩餘的字串；如果最後字串長度為0，那麼就找到了能分割字串的單片語成。這裡用一個hashMap儲存中間結果，否則會逾時。

代碼：

class Solution {     public List<String> wordBreak(String s, List<String> wordDict) {        return DFS(s, wordDict, new HashMap<String, LinkedList<String>>());    }    List<String> DFS(String s,List<String> wordDict,HashMap<String,LinkedList<String>> map){        if(map.containsKey(s))            return map.get(s);        LinkedList<String> res = new LinkedList<>();        if(s.length() == 0){            res.add("");            return res;        }        for(String word : wordDict){            if(s.startsWith(word)){                List<String> subList = DFS(s.substring(word.length()),wordDict,map);                for(String sub : subList){                    res.add(word + (sub.isEmpty() ? "":" ")+ sub);                }            }        }        map.put(s,res);        return res;    }}

 

[LeetCode] 140. Word Break II java