leetcode WordBreak
z
 2019-04-09 10:36:27   
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import java.util.HashMap;
import java.util.HashSet;
import java.util.List;

public class WordBreak {
  /**
   * 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.
   *
   * Note:
   *
   * The same word in the dictionary may be reused multiple times in the segmentation.
   * You may assume the dictionary does not contain duplicate words.
   * Example 1:
   *
   * Input: s = "leetcode", wordDict = ["leet", "code"]
   * Output: true
   * Explanation: Return true because "leetcode" can be segmented as "leet code".
   * Example 2:
   *
   * Input: s = "applepenapple", wordDict = ["apple", "pen"]
   * Output: true
   * Explanation: Return true because "applepenapple" can be segmented as "apple pen apple".
   *              Note that you are allowed to reuse a dictionary word.
   * Example 3:
   *
   * Input: s = "catsandog", wordDict = ["cats", "dog", "sand", "and", "cat"]
   * Output: false
   */
  public boolean wordBreak(String s, List<String> wordDict) {
    boolean[] dp = new boolean[s.length()+1];
    HashSet<String> hs = new HashSet<>();
    dp[0] = true;

    hs.addAll(wordDict);

    for (int i=1; i<=wordDict.size(); i++) {
      for (int j=0; j<i; i++) {
        if (dp[j] && hs.contains(s.substring(j+1, i)))
          dp[i] = true;
      }
    }
    return dp[s.length()];
  }
  public static void mian(String[] args) {

  }
}