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.

WordBreak.java

// wordBreak("facebook", ["face", "book"]) -> true
public boolean wordBreak(String s, List<String> wordDict) {
    Set<String> set = new HashSet<>(wordDict);
    if(set.contains(s))
        return true;

    Queue<Integer> queue = new LinkedList<>();
    Set<Integer> visited = new HashSet<>();
    queue.add(0);
    visited.add(0);

    while(queue.size() > 0) {
        int start = queue.poll();
        for(int end = start+1; end <= s.length(); end++) {
            if(visited.contains(end)) continue;
            if(set.contains(s.substring(start, end))) {
                if(end == s.length())
                    return true;
                queue.add(end);
                visited.add(end);
            }
        }
    }

    return false;
}