题目描述(Medium)
Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequence of one or more dictionary words.
Note:
- The same word in the dictionary may be reused multiple times in the segmentation.
- You may assume the dictionary does not contain duplicate words.
题目链接
https://leetcode.com/problems/word-break/description/
Example 1:
Input: s = "leetcode", wordDict = ["leet", "code"]
Output: true
Explanation: Return true because "leetcode" can be segmented as "leet code".
Example 2:
Input: s = "applepenapple", wordDict = ["apple", "pen"]
Output: true
Explanation: Return true because "applepenapple" can be segmented as "apple pen apple".
Note that you are allowed to reuse a dictionary word.
Example 3:
Input: s = "catsandog", wordDict = ["cats", "dog", "sand", "and", "cat"]
Output: false
算法分析
设状态为f(i),表示s[0,i]是否可以分词,则状态转移方程为
提交代码:
class Solution {
public:
bool wordBreak(string s, vector<string>& wordDict) {
const int n = s.size();
vector<bool> f(n + 1, false);
f[0] = true;
for (int i = 1; i <= n; ++i) {
for (int j = i - 1; j >= 0; --j) {
if (f[j] && find(wordDict.begin(), wordDict.end(),
s.substr(j, i - j)) != wordDict.end()) {
f[i] = true;
break;
}
}
}
return f[n];
}
};