HDU 1277 全文检索 (Trie树应用 好题)

全文检索

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 1304    Accepted Submission(s): 416

Problem Description

我们大家经常用google检索信息，但是检索信息的程序是很困难编写的；现在请你编写一个简单的全文检索程序。
问题的描述是这样的：给定一个信息流文件，信息完全有数字组成，数字个数不超过60000个，但也不少于60个；再给定一个关键字集合，其中关键字个数不超过10000个，每个关键字的信息数字不超过60个，但也不少于5个；两个不同的关键字的前4个数字是不相同的；由于流文件太长，已经把它分成多行；请你编写一个程序检索出有那些关键字在文件中出现过。

 

Input

第一行是两个整数M，N；M表示数字信息的行数，N表示关键字的个数；接着是M行信息数字，然后是一个空行；再接着是N行关键字；每个关键字的形式是：[Key No. 1] 84336606737854833158。

 

Output

输出只有一行，如果检索到有关键字出现，则依次输出，但不能重复，中间有空格，形式如：Found key: [Key No. 9] [Key No. 5]；如果没找到，则输出形如：No key can be found !。

 

Sample Input

20 10646371829920732613433350295911348731863560763634906583816269637943246892596447991938395877747771811648872332524287543417420073458038799863383943942530626367011418831418830378814827679789991249141417051280978492595526784382732523080941390128848936060512743730770176538411912533308591624872304820548423057714962038959390276719431970894771269272915078424294911604285668850536322870175463184619212279227080486085232196545993274120348544992476883699966392847818898765000210113407285843826588950728649155284642040381621412034311030525211673826615398392584951483398200573382259746978916038978673319211750951759887080899375947416778162964542298155439321112519055818097642777682095251801728347934613082147096788006630252328830397651057159088107635467760822355648170303701893489665828841446069075452303785944262412169703756833446978261465128188378490310770144518810438159567647733036073099159346768788307780542503526691711872185060586699672220882332373316019934540754940773329948050821544112511169610221737386427076709247489217919035158663949436676762790541915664544880091332011868983231199331629190771638894322709719381139120258155869538381417179544000361739177065479939154438487026200359760114591903421347697[Key No. 1] 934134543994403697353070375063[Key No. 2] 261985859328131064098820791211[Key No. 3] 306654944587896551585198958148[Key No. 4] 338705582224622197932744664740[Key No. 5] 619212279227080486085232196545[Key No. 6] 333721611669515948347341113196[Key No. 7] 558413268297940936497001402385[Key No. 8] 212078302886403292548019629313[Key No. 9] 877747771811648872332524287543[Key No. 10] 488616113330539801137218227609

 

Sample Output

Found key: [Key No. 9] [Key No. 5]

 

Author

Cai Minglun

 

Source

杭电ACM集训队训练赛（VI）

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1277

题目分析：网上貌似都是ac自动机搞的，这里用trie树搞一下，跑了62ms，读入用getchar记录下换行次数，对key字符串建字典树，枚举流文件的后缀到字典树中查找，再用hash标记一下

#include <cstdio>#include <cstring>char t[60005], tmp[10], key[65];bool hash[60005];struct node{    node *next[10];    int id;    node()    {        memset(next, NULL, sizeof(next));        id = -1;    }};void Insert(node *p, char *s, int id){    for(int i = 0; s[i] != '\0'; i++)    {        int idx = s[i] - '0';        if(p -> next[idx] == NULL)            p -> next[idx] = new node();        p = p -> next[idx];    }    p -> id = id;}void Search(node *p, char *s){    for(int i = 0; s[i] != '\0'; i++)    {        int idx = s[i] - '0';        if(p -> id != -1 && !hash[p -> id])        {            printf(" [Key No. %d]", p -> id);            hash[p -> id] = true;        }        if(p -> next[idx] == NULL)            return;        p = p -> next[idx];    }}int main(){    int n, m, cnt1 = 0, cnt2 = 0;    scanf("%d %d", &m, &n);     getchar();    while(cnt2 < m)    {        char ch = getchar();        if(ch == '\n')            cnt2++;        else            t[cnt1++] = ch;    }    t[cnt1] = '\0';    node *root = new node();    memset(hash, false, sizeof(hash));    for(int i = 1; i <= n; i++)    {        //tmp读取"[Key"，"No."，"1] "这些没用字符串        scanf("%s%s%s%s", tmp, tmp, tmp, key);        Insert(root, key, i);    }    printf("Found key:");    for(int i = 0; t[i] != '\0'; i++)        Search(root, t + i);    printf("\n");}