题目描述
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. You may assume the dictionary does not contain duplicate words.
Example
given s = "leetcode",
dict = ["leet", "code"].
Return true because "leetcode" can be segmented as "leet code".
解题思路
不需要记录具体结果同时大问题可以被分割成小问题，符合DP特征
Java代码实现
/*
递归有重复计算：当在循环到时候，会多次计算从i到j的子序列是否存在于字典中
故而考虑使用DP： dp(i) = dp(j) && s[j, i) in dict
*/
class Solution {
public boolean wordBreak(String s, List<String> wordDict) {
if (wordDict == null || wordDict.isEmpty()) {
return false;
}
Set wordSet = new HashSet(wordDict);
// 表示字符串的前i项可以被分割
// 因为substring取不到第i项，所以需要多一格
boolean result[] = new boolean[s.length() + 1];
result[0] = true;
for (int i = 1; i <= s.length(); i++) {
for (int j = 0; j < i; j++) {
if (result[j] && wordSet.contains(s.substring(j, i))) {
result[i] = true;
break;
}
}
}
return result[s.length()];
}
}
