hdu 1277 全文检索 ac 自动机

好纠结啊，就是因为一个小小的错误，导致一错再错！一开始是这样写的：

p = (p == root) ? p : p->child[index] ;

我觉得跟另一种写法没什么区别啊！？但是后来想一想，区别还是有的，只不过自己看不太清楚而已～～～

发现网上几乎没有此题的解题报告，于是贴出来，大家共勉吧～～～

/* THE PROGRAM IS MADE BY PYY */

/*----------------------------------------------------------------------------//

Copyright (c) 2011 panyanyany All rights reserved.

URL : http://acm.hdu.edu.cn/showproblem.php?pid=1277

Name : hdu 1277 ( 全文检索 )

Date : Friday, June 24, 2011

Time Stage : Many days

Result:

4088782	2011-06-24 22:10:34	Accepted	1277	125MS	19304K	4346 B	C++	pyy
4088768	2011-06-24 22:05:15	Wrong Answer	1277	0MS	240K	4218 B	C++	pyy

Test Data:

Review:

//----------------------------------------------------------------------------*/

#include <stdio.h> #include <string.h> #include <stdlib.h> #define SZ_MODEL 60001 #define SZ_PATN 66 #define NUM_PATN 10001 #define NUM_ELEM 10 #define FIRST_ELEM ('0') typedef struct tagNODE { int cnt, id ; struct tagNODE *fail, *child[NUM_ELEM] ; } NODE ; NODE *trie[NUM_PATN * SZ_PATN], *queue[NUM_PATN * SZ_PATN], *p, *root ; char amodel[SZ_MODEL], apattern[SZ_PATN] ; int line, keyword, len, num, count, cursor, find ; // 两个数组是必须的，一个用来记录先后顺序，一个用来判断是否已经出现过 int indices[NUM_PATN], repeat[NUM_PATN] ; void initialization () { len = 0 ; cursor = 0 ; find = 0 ; trie[cursor++] = (NODE *) calloc (1, sizeof (NODE)) ; memset (repeat, 0, sizeof (repeat)) ; root = *trie ; } void recycle () { while (cursor--) { free (trie[cursor]) ; } } void makeTrie () { char *s = apattern ; int index ; p = root ; while (*s) { index = *s++ - FIRST_ELEM ; // printf ("%d ", index) ; if (! (p->child[index])) { trie[cursor] = (NODE *) calloc (1, sizeof (NODE)) ; memset (trie[cursor], 0, sizeof (trie[cursor])) ; //----------------------------- p->child[index] = trie[cursor++] ; } p = p->child[index] ; } ++p->cnt ; // 多余的变量 p->id = num ; } void makeFail () { int head, tial, i ; NODE *tmpFail ; head = tial = 0 ; // initialize index root->fail = 0 ; for (i = 0 ; i < NUM_ELEM ; ++i) { if (root->child[i]) { root->child[i]->fail = root ; queue[tial++] = root->child[i] ; } } while (head != tial) { p = queue[head++] ; for (i = 0 ; i < NUM_ELEM ; ++i) { if (p->child[i]) { queue[tial++] = p->child[i] ; // enqueue //-------------- make failure pointer----------------------- tmpFail = p->fail ; while (tmpFail) { if (tmpFail->child[i]) { p->child[i]->fail = tmpFail->child[i] ; break ; } tmpFail = tmpFail->fail ; } if (!tmpFail) p->child[i]->fail = root ; } } } } void acAutomation () { NODE *tmp ; char *s = amodel ; int index ; p = root ; while (*s) { index = *s++ - FIRST_ELEM ; while (p->child[index] == NULL && p != root) p = p->fail ; /* 此处切忌使用 p = (p == root) ? p : p->child[index] ; 这样的语句。 p 的下一个值不能通过 是否与 root 相等来判断 */ p = (p->child[index] == NULL) ? p : p->child[index] ; tmp = p ; while (tmp->id) { if (!repeat[tmp->id]) { indices[find++] = tmp->id ; repeat[tmp->id] = 1 ; } tmp->id = 0 ; tmp = tmp->fail ; } } } int main () { int i ; char c ; // freopen ("test.txt", "r", stdin) ; while (scanf ("%d%d", &line, &keyword) != EOF) { initialization () ; while (line--) { scanf ("%s%c", amodel + len, &c) ; // %c 和 c 是读取 '/n'用的， // 不能这样写 ： scanf ("%s/n", amodel + len) ; 下同 len = strlen (amodel) ; } getchar () ; // 注意吸收掉一个空行 while (keyword--) { scanf ("[Key No. %d] %s%c", &num, apattern, &c) ; makeTrie () ; } makeFail () ; acAutomation () ; if (find) { printf ("Found key:") ; for (i = 0 ; i < find ; ++i) printf (" [Key No. %d]", indices[i]) ; puts ("") ; } else puts ("No key can be found !") ; recycle () ; } return 0 ; }