LeetCode:Word Break

Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words.

For example, given

s =

"leetcode"

,

dict =

["leet", "code"]

.

Return true because

"leetcode"

can be segmented as

"leet
 code"

.

动态规划:用f(i,j)表示字符串S从i到j的子串是否可分割，则有：f(0,n) = f(0,i) && f(i,n)

public boolean wordBreak(String s, Set<String> dict) {
		List<Integer> list = new ArrayList<Integer>();
		for (int i = s.length() - 1; i >= 0; i--) {
			String sub = s.substring(i);
			if (dict.contains(sub)) {
				list.add(i);
			} else {
				for (Integer index : list) {
					sub = s.substring(i, index);
					if (dict.contains(sub)) {
						list.add(i);
						break;
					}
				}
			}
		}
		if (list.isEmpty()) {
			return false;
		} else {
			Integer index = list.get(list.size() - 1);
			return index == 0;
		}

	}