模板

Trie字典樹大致可以分為兩種實現方式，一種是陣列，另一種是指標，那麼我們就整理了兩個模板：

陣列的實現：

#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <map>
using namespace std;
const int N = 1000000;
int ch[N][26],val[N],tot;
//陣列實現的話，總是拿不準ch陣列的大小，我們不確定生成的節點會有多少
void Init()
{
    memset(ch[0],0,sizeof(ch[0]));
    tot = 1;
    memset(val,0,sizeof(val));
}


void Insert(char *s,int x)
{
    int u = 0,len = strlen(s);
    for(int i =0 ;i < len;i ++)
    {
        int v = s[i]-'a';
        if(!ch[u][v])
        {
            memset(ch[tot],0,sizeof(ch[tot]));
            val[tot] = 0;
            ch[u][v] = tot ++;
        }
        u = ch[u][v];
    }
    val[u] = x;//結尾位置設定為權重，其餘位置都設定為0
}


int Find(char *s)
{
    int u = 0,len = strlen(s);
    for(int i =0;i < len;i ++)
    {
        int v = s[i]-'a';
        if(!ch[u][v]) return 0;
        u = ch[u][v];
    }
    return val[u];
}


void Del(char  *s)
{
    int  u = 0,len = strlen(s);
    for(int i =0 ;i < len;i ++)
    {
        int v = s[i] - 'a';
        if(!ch[u][v]) return ;
        u = ch[u][v];
    }
    val[u] = 0;//刪除時就是將最後一個位置的權值設定為0
}
 

指標實現

#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <map>
using namespace std;
//指標實現較為方便，並且也很容易理解
struct Trie
{
    Trie *next[26];
    int val;
};
Trie *root;
void Init()
{
    root = (Trie *)malloc(sizeof(Trie));
    for(int i = 0;i < 26;i ++)
        root->next[i] = NULL;
    root->val = 0;
}
void Insert(char *s)
{
    Trie *p = root,*q;
    int len = strlen(s);
    for(int i = 0;i < len;i ++)
    {
        int v = s[i] - 'a';
        if(p->next[v] == NULL)
        {
            q = (Trie *)malloc(sizeof(Trie));
            q->val = 0;
            for(int j = 0;j < 26;j ++)
                q->next[j] = NULL;
            p->next[v] = q;
        }
        p = p->next[v];
    }
    p->val = 1;
}

int Find(char *s)
{
    int len = strlen(s);
    Trie *p = root;
    for(int i =0 ;i < len;i ++)
    {
        int v = s[i] - 'a';
        p = p->next[v];
        if(p == NULL)  return -1;
    }
    return p->val;
}

void Del(Trie *s)
{
    if(s == NULL)
        return ;
    for(int i =0;i < 26;i ++)
        if(s->next[i])
            Del(s->next[i]);
    delete s;
}
 

栗子

#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#include<cmath>

using namespace std;
const int N = 1000000;
int sz;
int ch[N][26];
int val[N];
struct Trie
{
    Trie(){
        sz = 1;//這裡要把0節點空出來，作為全部的根節點
        memset(ch[0],0,sizeof(ch[0]));
        memset(val,0,sizeof(val));
    }

    int idx(char c)
    {
        return c-'a';
    }
    void Insert(char *s,int v)
    {
        int u = 0,len = strlen(s);
        for(int i =0 ;i < len;i ++)
        {
            int c = idx(s[i]);
            if(!ch[u][c])//表示這個節點重新作為一個新的節點，下面仍然還有26個子節點
            {
                memset(ch[sz],0,sizeof(ch[sz]));
                val[sz] = 0;
                ch[u][c] = sz++;
            }
            u = ch[u][c];
            val[u] ++;
        }
    }
    int Read(char *s)
    {
        int u = 0,len = strlen(s);
        for(int i = 0;i < len;i ++)
        {
            int c = idx(s[i]);
            if(!ch[u][c])  return -1;
            else  u = ch[u][c];
        }
        if(val[u] == 0)
            return 1;
        else
            return 2;
    }
    int Get_num(char *s)
    {
        int u = 0,len = strlen(s);
        for(int i = 0;i < len;i ++)
        {
            int c = idx(s[i]);
            if(!ch[u][c]) return 0;
            else u = ch[u][c];
        }
        return val[u];
    }
};

int main()
{
    Trie T;
    char s[15];
    while(1)
    {
        gets(s);
        if(s[0] == '\0') break;
        T.Insert(s,1);
    }
    while(gets(s))
    {
        printf("%d\n",T.Get_num(s));
    }
    return 0;
}
 

#include <iostream>
#include <cstdio>
#include <string>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <map>
using namespace std;
struct Trie
{
    Trie *next[26];
    char *val;
};
Trie *root;
void Init()
{
    root = (Trie *)malloc(sizeof(Trie));
    for(int i = 0;i < 26;i ++)
        root->next[i] = NULL;
    root->val = NULL;
}
void Insert(char *s,char *str)
{
    Trie *p = root,*q;
    int len = strlen(s);
    for(int i = 0;i < len;i ++)
    {
        int v = s[i] - 'a';
        if(p->next[v] == NULL)
        {
            q = (Trie *)malloc(sizeof(Trie));
            q->val = NULL;
            for(int j = 0;j < 26;j ++)
                q->next[j] = NULL;
            p->next[v] = q;
        }
        p = p->next[v];
    }
    p->val = new char[11];
    strcpy(p->val,str);
}

void Find(char *s)
{
    int len = strlen(s);
    Trie *p = root;
    for(int i =0 ;i < len;i ++)
    {
        int v = s[i] - 'a';
        p = p->next[v];
        if(p == NULL)  {printf("%s",s);return ;}
    }
    if(p->val)  printf("%s",p->val);
    else printf("%s",s);
}

void Del(Trie *s)
{
    if(s == NULL)
        return ;
    for(int i =0 ;i < 26;i ++)
    {
        if(s->next[i])
            Del(s->next[i]);
    }
    delete s->val;
    delete s;
}

int main()
{
    char s[15],s1[15];
    Init();
    scanf("%s",s);
    while(scanf("%s %s\n",s,s1) && strcmp(s,"END"))
    {
        Insert(s1,s);
    }
    char str[3100],part[100];
    while(gets(str) && strcmp(str,"END"))
    {
        int index = 0;
        int len = strlen(str);
        for(int i = 0;i < len;i ++)
        {
            if(islower(str[i]))
                part[index++] = str[i];
            else
            {
                part[index] = '\0';
                Find(part);
                index = 0;
                printf("%c",str[i]);
            }
        }
        puts("");
    }
}

參考部落格