字典树模板（java）

class Trie{private int SIZE=26;private TrieNode root;//字典树的根Trie(){//初始化字典树root=new TrieNode();}private class TrieNode{//字典树节点private int num;//有多少单词通过这个节点,即节点字符出现的次数private TrieNode[]  son;//所有的儿子节点private boolean isEnd;//是不是最后一个节点private char val;//节点的值TrieNode(){num=1;son=new TrieNode[SIZE];isEnd=false;}}//建立字典树public void insert(String str){//在字典树中插入一个单词if(str==null||str.length()==0){return ;}TrieNode node=root;char[] letters=str.toCharArray();for(int i=0,len=str.length();i < len;i++){int pos=letters[i]-'a';if(node.son[pos]==null){node.son[pos]=new TrieNode();node.son[pos].val=letters[i];}else{node.son[pos].num++;}node=node.son[pos];}node.isEnd=true;}//计算单词前缀的数量public int countPrefix(String prefix){if(prefix==null || prefix.length()==0){return -1;}TrieNode node=root;char[] letters=prefix.toCharArray();for(int i=0,len=prefix.length();i<len;i++){int pos=letters[i]-'a';if(node.son[pos]==null){return 0;}else{node=node.son[pos];}}return node.num;}//在字典树中查找一个完全匹配的单词.public boolean has(String str){if(str==null || str.length()==0){return false;}TrieNode node=root;char[] letters = str.toCharArray();for(int i=0,len=str.length();i<len;i++){int pos= letters[i]-'a';if(node.son[pos]!=null){node=node.son[pos];}else{return false;}}return node.isEnd;}//前序遍历字典树.public void preTraverse(TrieNode node){if(node!=null){System.out.print(node.val+"-");for(TrieNode child:node.son){preTraverse(child);}}}public TrieNode getRoot(){return this.root;}public static void main(String[] args){Trie tree=new Trie();String[] strs={"banana","band","bee","absolute","acm",};String[]prefix={"ba","b","band","abc",};for(String str:strs){tree.insert(str);}System.out.println(tree.has("abc"));tree.preTraverse(tree.getRoot());System.out.println();for(String pre:prefix){int num=tree.countPrefix(pre);System.out.println(pre+" "+num);}}}

<pre name="code" class="cpp">hdu 1251

#include<string>#include<cstring>#include<iostream>#include<cstdio>using namespace std;#define SIZE 26struct TNode{    int num;    char val;    TNode* son[SIZE];    bool isEnd;    TNode(){        num = 1;        isEnd = false;        for(int i = 0; i < SIZE; i ++)            son[i] = NULL;    }};class Trie{private:    struct TNode* root;public:    Trie(){        root = new TNode();    }    void insert(char* str){        if(strlen(str) == 0){            return ;        }        struct TNode* node = root;        for(int i = 0, len = strlen(str); i < len; i ++){            int pos = str[i] - 'a';            if(node->son[pos] == NULL){                node->son[pos] = new TNode();                node->son[pos]->val = str[i];            }else{                node->son[pos]->num ++;            }            node = node->son[pos];        }        node->isEnd = true;    }    int countPrefix(char* prefix){        if(strlen(prefix) == 0){            return 0;        }        struct TNode* node = root;        for(int i=0, len = strlen(prefix); i < len; i ++){            int pos = prefix[i] - 'a';            if(node->son[pos] != NULL){                node = node->son[pos];            }else{                return 0;            }        }        return node->num;    }};int main(){    Trie* node = new Trie();    char str[1010];    while(gets(str)){        if(strlen(str) == 0){            break;        }        node->insert(str);    }    while(scanf("%s", str) != EOF){        printf("%d\n", node->countPrefix(str));    }    return 0;}

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