_139_WordBreak.java

package leetcode_1To300;

import java.util.List;

/**
 * 本代码来自 Cspiration，由 @Cspiration 提供
 * 题目来源：http://leetcode.com
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 * - 版权所有，转发请注明出处
 */
public class _139_WordBreak {

    /**
     * 139. Word Break
     * 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".

     time : O(n^2) ～ O(n^4);
     space : O(n);

     contains 时间：O(n)
     substring 时间：O(n)

     s = "leetcode",
     dict = ["leet", "code"]


     * @param s
     * @param wordDict
     * @return
     */

    public boolean wordBreak(String s, List<String> wordDict) {
        boolean[] dp = new boolean[s.length() + 1];
        dp[0] = true;
        for (int i = 1; i <= s.length(); i++) {
            for (int j = 0; j < i; j++) {
                if (dp[j] && wordDict.contains(s.substring(j, i))) {
                    dp[i] = true;
                    break;
                }
            }
        }
        return dp[s.length()];
    }
}