【POJ3461】【KMP】Oulipo

Description

The French author Georges Perec (1936–1982) once wrote a book, La disparition, without the letter 'e'. He was a member of the Oulipo group. A quote from the book:

Tout avait Pair normal, mais tout s’affirmait faux. Tout avait Fair normal, d’abord, puis surgissait l’inhumain, l’affolant. Il aurait voulu savoir où s’articulait l’association qui l’unissait au roman : stir son tapis, assaillant à tout instant son imagination, l’intuition d’un tabou, la vision d’un mal obscur, d’un quoi vacant, d’un non-dit : la vision, l’avision d’un oubli commandant tout, où s’abolissait la raison : tout avait l’air normal mais…

Perec would probably have scored high (or rather, low) in the following contest. People are asked to write a perhaps even meaningful text on some subject with as few occurrences of a given “word” as possible. Our task is to provide the jury with a program that counts these occurrences, in order to obtain a ranking of the competitors. These competitors often write very long texts with nonsense meaning; a sequence of 500,000 consecutive 'T's is not unusual. And they never use spaces.

So we want to quickly find out how often a word, i.e., a given string, occurs in a text. More formally: given the alphabet {'A', 'B', 'C', …, 'Z'} and two finite strings over that alphabet, a word W and a text T, count the number of occurrences of W in T. All the consecutive characters of W must exactly match consecutive characters of T. Occurrences may overlap.

Input

The first line of the input file contains a single number: the number of test cases to follow. Each test case has the following format:

• One line with the word W, a string over {'A', 'B', 'C', …, 'Z'}, with 1 ≤ |W| ≤ 10,000 (here |W| denotes the length of the string W).
• One line with the text T, a string over {'A', 'B', 'C', …, 'Z'}, with |W| ≤ |T| ≤ 1,000,000.

Output

For every test case in the input file, the output should contain a single number, on a single line: the number of occurrences of the word W in the text T.

Sample Input

3
BAPC
BAPC
AZA
AZAZAZA
VERDI
AVERDXIVYERDIAN

Sample Output

1
3
0

Source

BAPC 2006 Qualification

【分析】

模板

 /*
 宋代李之仪
 卜算子·我住长江头
 我住长江头，君住长江尾。日日思君不见君，共饮长江水。
 此水几时休，此恨何时已。只愿君心似我心，定不负相思意。
 */
 #include <iostream>
 #include <cstdio>
 #include <algorithm>
 #include <cstring>
 #include <vector>
 #include <utility>
 #include <iomanip>
 #include <string>
 #include <cmath>
 #include <queue>
 #include <assert.h>
 #include <map>
 #include <ctime>
 #include <cstdlib>
 #include <stack>
 #define LOCAL
 const int MAXN =  + ;
 const int INF = ;
 const int SIZE = ;
 const int MAXM =  + ;
 const int maxnode =  0x7fffffff + ;
 using namespace std;
 int l1, l2;
 char a[MAXN], b[MAXN];
 int next[];//不用开太大了..
 void getNext(){
      //初始化next数组
      next[] = ;
      int j = ;
      for (int i = ; i <= l1; i++){
          while (j >  && a[j + ] != a[i]) j = next[j];
          if (a[j + ] == a[i]) j++;
          next[i] = j;
      }
      return;
 }
 int kmp(){
     int j = , cnt = ;
     for (int i = ; i <= l2; i++){
         while (j >  && a[j + ] != b[i]) j = next[j];
         if (a[j + ] == b[i]) j++;
         if (j == l1){
            cnt++;
            j = next[j];//回到上一个匹配点
         }
     }
     return cnt;
 }

 void init(){
      scanf("%s", a + );
      scanf("%s", b + );
      l1 = strlen(a + );
      l2 = strlen(b + );
 }

 int main(){
     int T;

     scanf("%d", &T);
     while (T--){
           init();
           getNext();
           printf("%d\n", kmp());
     }
     /*scanf("%s", a + 1);
     l1 = strlen(a + 1);
     getNext();
     for (int i = 1; i <= l1; i++) printf("%d ", next[i]);*/
     return ;
 }