[Leetcode] Word Break II
2014-04-22 17:16
302 查看
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 =
dict =
A solution is
这题不能直接DFS,否则会超时,联想到上一题,可以跟上题一样先动态规划,判断能否被break,如果s不能被break,那么也没有DFS的必要了,另外在DFS时也可以再利用dp所存的信息从而可以大大得剪掉不必要的操作。
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"].
这题不能直接DFS,否则会超时,联想到上一题,可以跟上题一样先动态规划,判断能否被break,如果s不能被break,那么也没有DFS的必要了,另外在DFS时也可以再利用dp所存的信息从而可以大大得剪掉不必要的操作。
class Solution { public: void breakWord(vector<string> &res, string &s, unordered_set<string> &dict, string str, int idx, vector<bool> &dp) { string substr; for (int len = 1; idx + len < s.length() + 1; ++len) { if (dp[idx + len] && dict.count(s.substr(idx,len)) > 0) { substr = s.substr(idx, len); if (idx + len < s.length()) { breakWord(res, s, dict, str + substr + " ", idx + len, dp); } else { res.push_back(str + substr); return; } } } } vector<string> wordBreak(string s, unordered_set<string> &dict) { vector<bool> dp(s.length() + 1, false); dp[0] = true; for (int i = 0; i < s.length(); ++i) { if (dp[i]) { for (int len = 1; i + len < s.length() + 1; ++len) { if (dict.count(s.substr(i, len)) > 0) { dp[i + len] = true; } } } } vector<string> res; if (dp[s.length()]) breakWord(res, s, dict, "", 0, dp); return res; } };
相关文章推荐
- LEETCODE: Word Break II
- [LeetCode] WordBreak II, Solution
- [LeetCode] Word Break && Word Break II
- leetcode-Word Break II
- [LeetCode] WordBreak II, Solution
- [LeetCode] Word Break II
- Leetcode: Word Break II
- 【LeetCode】Word Break II 动态规划
- Leetcode 140. Word Break II
- [LeetCode] 140. Word Break II 单词拆分II
- [Leetcode] 140. Word Break II 解题报告
- 【leetcode】Word Break II
- LeetCode--Word Break II 拆分词句之二
- [C++]LeetCode: 113 Word Break II (DP && Backtacking) 求解拆分组合
- Leetcode 140 Word Break II
- [LeetCode] Word Break II
- Leetcode -- Word Break II
- Leetcode: Word Break II
- 【LeetCode】140. Word Break II
- Leetcode---word Break II