hihoCoder 1014 Trie树 字典树模板

题目：

http://hihocoder.com/problemset/problem/1014

题意：

首先给出一些字符串，代表字典里的单词。然后再给出一些字符串，询问字典中以当前字符串为前缀的单词个数

思路：

字典树模板题。留个模板
动态字典树，特点是好写好理解，确定是效率慢，有可能TLE

//多实例记得调用trie_del函数清空字典树，单实例无所谓#include <bits/stdc++.h>using namespace std;const int N = 100000 + 10, INF = 0x3f3f3f3f;struct trie{    int val;    trie *next[26];    trie()    {        val = 0;        memset(next, 0, sizeof next);    }}*root;void trie_insert(char *s){    trie *p = root;    for(int i = 0; s[i]; i++)    {        int j = s[i] - 'a';        if(p->next[j] == NULL) p->next[j] = new trie;        p->next[j]->val++;        p = p->next[j];    }}int trie_query(char *s){    trie *p = root;    for(int i = 0; s[i]; i++)    {        int j = s[i] - 'a';        if(p->next[j] == NULL) return 0;        p = p->next[j];    }    return p->val;}void trie_del(trie *p){    for(int i = 0; i < 26; i++)        if(p->next[i] != NULL) trie_del(p->next[i]);    delete p;}int main(){    int n, m;    root = new trie;    char s[20];    scanf("%d", &n);    for(int i = 1; i <= n; i++)    {        scanf("%s", s);        trie_insert(s);    }    scanf("%d", &m);    for(int i = 1; i <= m; i++)    {        scanf("%s", s);        printf("%d\n", trie_query(s));    }    trie_del(root);    return 0;}

静态字典树，特点是速度快，但需要的空间稍大，小心空间开小导致的RE

//这个模板长的很像动态字典树#include <bits/stdc++.h>using namespace std;const int N = 100000 + 10;struct node{    int val;    node *next[26];}trie[N*10], *root;int tot;char s[N];node* node_init(){    trie[tot].val = 0;    memset(trie[tot].next, 0, sizeof trie[tot].next);    return trie + tot++;}void trie_insert(char *s){    node *p = root;    for(int i = 0; s[i]; i++)    {        int j = s[i] - 'a';        if(p->next[j] == NULL) p->next[j] = node_init();        p->next[j]->val++;        p = p->next[j];    }}int trie_query(char *s){    node *p = root;    for(int i = 0; s[i]; i++)    {        int j = s[i] - 'a';        if(p->next[j] == NULL) return 0;        p = p->next[j];    }    return p->val;}int main(){    int n, m;    tot = 1;    root = trie + 0;    scanf("%d", &n);    for(int i = 1; i <= n; i++)    {        scanf("%s", s);        trie_insert(s);    }    scanf("%d", &m);    for(int i = 1; i <= m; i++)    {        scanf("%s", s);        printf("%d\n", trie_query(s));    }    return 0;}

//多实例清空字典树时将sz初始化为1即可#include <bits/stdc++.h>using namespace std;const int N = 100000 + 10, INF = 0x3f3f3f3f;struct node{    int val;    int next[26];}trie[N*5];int sz;int node_init(){    memset(trie[sz].next, 0, sizeof trie[sz].next);    trie[sz].val = 0;    return sz++;}void trie_insert(char *s){    int id = 0;    for(int i = 0; s[i]; i++)    {        int j = s[i] - 'a';        if(trie[id].next[j] == 0) trie[id].next[j] = node_init();        trie[trie[id].next[j]].val++;        id = trie[id].next[j];    }}int trie_query(char *s){    int id = 0;    for(int i = 0; s[i]; i++)    {        int j = s[i] - 'a';        if(trie[id].next[j] == 0) return 0;        id = trie[id].next[j];    }    return trie[id].val;}int main(){    int n, m;    char s[20];    sz = 1;    memset(trie[0].next, 0, trie[0].next);    scanf("%d", &n);    for(int i = 1; i <= n; i++)    {        scanf("%s", s);        trie_insert(s);    }    scanf("%d", &m);    for(int i = 1; i <= m; i++)    {        scanf("%s", s);        printf("%d\n", trie_query(s));    }    return 0;}