// 耗时3ms

// 典型的DP问题

public boolean wordBreak(String s, List<String> wordDict) {

int n = s.length();

boolean[] dp = new boolean[n + 1];

dp[0] = true;

for (int i = 1; i <= s.length(); i++) {

for (String word : wordDict) {

int j = i - word.length();

if (j >= 0 && dp[j] && s.substring(j, i).equals(word)) {

dp[i] = true;

break;

}

}

}

return dp[n];

}