中文分詞--逆向最大匹配

上一篇文章中介紹了正向最大匹配，可以看到有時候效果不是很好，這裏在介紹一種逆向最大匹配的算法。詞典和匹配的字符串都和上一篇文章相同</span>

只是本算法是從後到前搜索字符串，然後找到最長的匹配結果輸出。上代碼

<pre code_snippet_id="331438" snippet_file_name="blog_20140507_2_819878" name="code" class="java">package com;


import java.util.ArrayList;
import java.util.List;


public class Segmentation1 {
    private List<String> dictionary = new ArrayList<String>();
    private String request = "北京大學生前來應聘";

    public void setDictionary() {
        dictionary.add("北京");
        dictionary.add("北京大學");
        dictionary.add("大學");
        dictionary.add("大學生");
        dictionary.add("生前");
        dictionary.add("前來");
        dictionary.add("應聘");
    }

    private boolean isIn(String s, List<String> list) {
        for(int i=0; i<list.size(); i++) {
            if(s.equals(list.get(i))) return true;
        }
        return false;
    }

    public String rightMax() {
        String response = "";
        String s = "";
        for(int i=request.length()-1; i>=0; i--) {
            s = request.charAt(i) + s;
            if(isIn(s, dictionary) && tailCount(s, dictionary)==1) {
                response = (s + "/") + response;
                s = "";
            } else if(tailCount(s, dictionary) > 0) {

            } else {
                response = (s + "/") + response;
                s = "";
            }
        }
        return response;
    }

    private int tailCount(String s, List<String> list) {
        int count = 0;
        for(int i=0; i<list.size(); i++) {
            if((s.length()<=list.get(i).length()) && (s.equals(list.get(i).substring(list.get(i).length()-s.length(), list.get(i).length())))) count ++;
        }
        return count;
    }

    public static void main(String[] args) {
        Segmentation1 seg = new Segmentation1();
        seg.setDictionary();
        String response2 = seg.rightMax();
        System.out.println(response2);
    }
}
</pre><br>
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<pre></pre>
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<p>可以看到運行結果是：北京/大學生/前來/應聘/</p>
<p>分詞效果很好</p>
<p><br>
</p>

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