B - Oulipo HDU - 1686

直接按照模板输出

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

#include<cstdio>
#include<cstring>
using namespace std;

const int max1 = 10005;
const int max2 = 1000005;
char a[max1];
char b[max2];
int next[max1];

void kmp_pre(char x[], int m){
    int i,j;
    j=next[0] = -1;
    i=0;
    while(i<m){
        while(j!= -1 && x[i] != x[j]) j = next[j];
        next[++i] = ++j;
    }
} 

int kmp(char x[], int m, char y[], int n){
    int i,j;
    int ans = 0;
    kmp_pre(x, m);
    i = j = 0;
    while(i < n){
        while(-1!=j&&y[i]!=x[j]) j = next[j];
        i++;j++;
        if(j >= m){
            ans++;
            j = next[j]; 
        }
    }
    return ans;
}

int main(){
    int t;
    scanf("%d", &t);
    while(t--){
        scanf("%s %s", a ,b);
        int k = kmp(a, strlen(a), b , strlen(b));
        printf("%d\n", k);
    }
    return 0;
}