字典树(前缀树)的实现(添加、删除、查找、查找前缀)

https://blog.csdn.net/zuochao_2013/article/details/79134714

//字典树(前缀树)的实现(添加、删除、查找、查找前缀)
public class DicTree{
    public  TrieNode root; //定义根节点
 
    //字典树构造函数初始化
    public DicTree()
    {
        root=new TrieNode();
    }
    //字典树节点的定义
     class TrieNode{
 
        public int path;
        public int end;
        public TrieNode[]map;
         //构造函数实现初始化
        public TrieNode()
        {
             path=0;
             end=0;
             map=new TrieNode[26];
        }
 
    }
 
    //(1)添加
    public  void insert(String word)
    {
       if(word==null)
       {
            return;
       }
       //字符串转数组
       char[]chs=word.toCharArray();
       TrieNode node=root;
       int index=0;
       for(int i=0;i<chs.length;i++)
       {
              index=chs[i]-'a';
              if(node.map[index]==null)
              {
                    node.map[index]=new TrieNode();
              }
              node=node.map[index];
              node.path++;
       }
       node.end++;
    }
   
    //(2)删除
    public  void delete(String word)
    {  
        //字典树中是否含有word单词
       if(search(word))
       {
            //字符串转数组
       char[]chs=word.toCharArray();
       TrieNode node=root;
       int index=0;
       for(int i=0;i<chs.length;i++)
       {
              index=chs[i]-'a';
              if(node.map[index].path--==1)
              {
                    node.map[index]=null;
                    return ;
              }
              node=node.map[index];
              
       }
       node.end--;
       } 
    }
    
    //(3)查找
    public  boolean  search(String word)
    {
         if(word==null)
         {
             return false;
         } 
        //字符串转数组
       char[]chs=word.toCharArray();
       TrieNode node=root;
       int index=0;
       for(int i=0;i<chs.length;i++)
       {
              index=chs[i]-'a';
              if(node.map[index]==null)
              {
                   
                    return  false;
              }
              node=node.map[index];
              
       }
         return node.end!=0;
    }
  
    //(4)查找前缀
    public  int PreSearch(String pre)
    {
        if(pre==null)
        {
            return 0;
        }
 
        char[]chs=pre.toCharArray();
        int index=0;
        TrieNode node=root;
        for(int i=0;i<chs.length;i++)
        {
             index=chs[i]-'a';
             if(node.map[index]==null)
             {
                 return 0;
             }
             node=node.map[index];
        }
       return node.path;
    }
 
    public static void main(String[]args)
    {
        //System.out.println("Hello");
        DicTree dicTree=new DicTree();
        String str1="abc";
        String str2="abcd";
        String str3="abd";
        String str4="b";
        String str5="bcd";
        String str6="efg";
        String str7="hik";
 
        dicTree.insert(str1);
        dicTree.insert(str2);
        dicTree.insert(str3);
        dicTree.insert(str4);
        dicTree.insert(str5);
        dicTree.insert(str6);
        dicTree.insert(str7);
 
        System.out.println(dicTree.search(str3));
        dicTree.delete(str3);
        System.out.println(dicTree.search(str3));
 
        System.out.println(dicTree.PreSearch(str3));
        System.out.println(dicTree.PreSearch(str1));
 
 
      
    }
}