题意 给你两个字符串p和s 求p在s中出现的次数 很裸的kmp
因为不止匹配一次 每次找到后还要循环j=next[j]的过程 知道到达s的终点
#include<cstdio>
#include<cstring>
using namespace std;
const int N = 10005, M = 1000005;
int next[N], ans, n;
char p[N], s[M];
void kmp ()
{
int lp = strlen (p), ls = strlen (s), i, j;
next[0] = -1, next[1] = i = 0;
while ( (++i) < lp)
{
j = next[i];
while (j != -1 && p[i] != p[j])
j = next[j];
next[i + 1] = j + 1;
}
i = j = 0;
while (i < ls)
{
if (j == -1 || s[i] == p[j])
{
++i, ++j;
if (j == lp) ++ans, j = next[j];
}
else j = next[j];
}
}
int main()
{
scanf ("%d", &n);
while (n--)
{
ans = 0;
scanf ("%s%s", p, s);
kmp ();
printf ("%d\n", ans);
}
return 0;
}
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:
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
POJ 3461 Oulipo(KMP字符串匹配),布布扣,bubuko.com
原文地址：http://blog.csdn.net/iooden/article/details/38563023
