| Time Limit: 1000MS | Memory Limit: 32768KB | 64bit IO Format: %I64d & %I64u |
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
KMP求匹配到模式串的个数，可以重叠（如样例2）
#include <cstdio>
#include <cstring>
using namespace std;
char w[10010], t[1000010];
void input()
{
scanf("%s%s", w, t);
}
void kmp_pre(char x[], int m, int next[])
{
int i, j;
j = next[0] = -1;
i = 0;
while (i < m)
{
while (-1 != j && x[i] != x[j])
j = next[j];
next[++i] = ++j;
}
}
int next[10010];
int kmp_count(char x[], int m, char y[], int n)
{
int i, j;
int ans = 0;
kmp_pre(x, m, next);
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;
}
void solve()
{
printf("%d\n", kmp_count(w, strlen(w), t, strlen(t)));
}
int main()
{
int T;
scanf("%d", &T);
while (T--)
{
input();
solve();
}
return 0;
}