hdu 1277Trie树

这题本来以为得DFA的，仔细审题以后发现，题目说每个关键字前4个字母不同(这意味着每个关键字结束的节点都是不同的)，而且长度不超过60，马上醒悟，只要用所有的关键字建一棵Trie树，然后把主串跑一遍就可以了，复杂度为主串长度*60，肯定能过啊。。。

/*
 * hdu1277/win.cpp
 * Created on: 2012-11-6
 * Author    : ben
 */
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
#include <stack>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <functional>
#include <numeric>
#include <cctype>
using namespace std;
const int child_num = 10;
const int MAXM = 60100;
const int MAXN = 10100;
char str[MAXM];
bool flags[MAXN];
const char base = '0';
typedef struct TrieNode {
    //子节点指针
    struct TrieNode *child[child_num];
    int num;
}TrieNode;
const int MAX_NODE_NUM = 300000;
TrieNode mymemory[MAX_NODE_NUM];
int cur_node_num = 0;
vector<int> ans;
inline TrieNode* newTrieNode() {
    //如需动态分配内存，则下句可改为TrieNode* node = new TrieNode();
    TrieNode* node = &mymemory[cur_node_num++];
    //初始化
    node->num = 0;
    memset(node->child, 0, sizeof(node->child));
    return node;
}
void insert_to_trie(TrieNode *root, const char *s, const int len, int num) {
    TrieNode *p = root;
    for (int i = 0; i < len; i++) {
        if (p->child[s[i] - base] == NULL) {
            p->child[s[i] - base] = newTrieNode();
        }
        p = p->child[s[i] - base];
    }
    p->num = num;
}
void work(TrieNode *p, char *s) {
    for(int i = 0; i < 60; i++) {
        if(p->num > 0) {
            ans.push_back(p->num);
            return ;
        }
        if(p->child[s[i] - base] == NULL) {
            return ;
        }
        p = p->child[s[i] - base];
    }
}
int main() {
#ifndef ONLINE_JUDGE
    freopen("data.in", "r", stdin);
#endif
    int M, N, t;
    scanf("%d%d", &M, &N);
    char temp[100];
    str[0] = 0;
    for(int i = 0; i < M; i++) {
        scanf("%s", temp);
        strcat(str, temp);
    }
    TrieNode *root = newTrieNode();
    for(int i = 0; i < N; i++) {
        scanf(" [Key No. %d] %s", &t, temp);
        insert_to_trie(root, temp, strlen(temp), t);
    }
    memset(flags, false, sizeof(flags));
    int len = strlen(str);
    for(int i = 0; i < len; i++) {
        work(root, str + i);
    }
    printf("Found key:");
    for(int i = 0, len = ans.size(); i < len; i++) {
        printf(" [Key No. %d]", ans[i]);
    }
    putchar('\n');
   return 0;
}