Description
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.
For example, given
s = "leetcode",
dict = ["leet", "code"].
Return true because "leetcode" can be segmented as "leet code".
UPDATE (2017/1/4):
The wordDict parameter had been changed to a list of strings (instead of a set of strings). Please reload the code definition to get the latest changes.
Solution
DP, time O(n * n * dictSize)
这道题用recursive解法会TLE，必须上DP啦。另外真是不懂wordDict为什么不是Set……
class Solution {
public boolean wordBreak(String s, List<String> wordDict) {
if (s == null || s.isEmpty()) {
return false;
}
int n = s.length();
boolean[] canBreak = new boolean[n + 1]; // s.substring(0, i) can break or not
canBreak[0] = true;
for (int i = 0; i < n; ++i) {
for (int j = i; j >= 0; --j) {
if (search(wordDict, s.substring(j, i + 1)) && canBreak[j]) {
canBreak[i + 1] = true;
break;
}
}
}
return canBreak[n];
}
public boolean search(List<String> dict, String s) {
for (String word : dict) {
if (word.equals(s)) {
return true;
}
}
return false;
}
}
