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>
#include<iostream>
using namespace std;
#define M 1000010
int ne[M];
char a[M], b[10010];
void GetNext()
{
int len = strlen(b);
int i = 0, j = -1;
while(i < len)
{
if(j == -1 || b[i] == b[j]){
ne[++i] = ++j;
}
else j = ne[j]; //回溯至上一个
}
}
int KmpCompare()
{
int lena = strlen(a);
int lenb = strlen(b);
int i = 0, j = 0, s = 0;
while(i<lena)
{
if(j == -1 || a[i] == b[j]){
j++;
i++;
//cout <<i << ' ' << j<<endl;
}
else j = ne[j];
if(j == lenb){
j = ne[j];
s++;
}
}
return s;
}
int main()
{
int t, s;
scanf("%d", &t);
while(t--){
memset(ne, -1, sizeof(ne));
scanf("%s", &b);
//cout<<b;
//getchar();
scanf("%s", &a);
//cout<<a;
GetNext();
s = KmpCompare();
printf("%d\n", s);
}
return 0;
}
tle了无数遍。。。气死了。。。一定要用scanf,即使要用 cin 也别忘了取消cin与stdin的同步