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| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 26781 | Accepted: 10672 |
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
Source
给出两个字符串 求一个字符串在另一个字符串中的次数tle了好几次
发现有while(i<strlen(s))这样的代码
好搓- -
改了就过了 以后要注意- -
#include<cstdio>
#include<cstring>
#define MAXN 1111111
int ans,next[MAXN];
char p[MAXN],t[MAXN];
void getnext(){
int j=0,k=-1;
next[0]=-1;
int l=strlen(p);
while(j<l){
if(k==-1||p[j]==p[k]){
j++;
k++;
if(p[j]!=p[k])
next[j]=k;
else next[j]=next[k];
}
else {
k=next[k];
}
}
}
void kmp(){
ans=0;
int i=0,j=0;
int l1=strlen(t),l2=strlen(p);
while(i<l1){
if(j==-1||t[i]==p[j]){
i++;
j++;
}
else j=next[j];
if(j==l2){
ans++;
j=next[j];
}
}
}
int main(){
int T;
scanf("%d",&T);
while(T--){
scanf("%s",p);
scanf("%s",t);
getnext();
kmp();
printf("%d\n",ans);
}
}
原文：http://blog.csdn.net/qq_16843991/article/details/44566797