poj3461 kmp模板题

Oulipo

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 18186 Accepted: 7299

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

3BAPCBAPCAZAAZAZAZAVERDIAVERDXIVYERDIAN

Sample Output

130

Source

BAPC 2006 Qualification

代码

#include <iostream>#include <string.h>#include <stdio.h>using namespace std;int ans;int next[1111111];char str1[11111],str2[1111111];void get_next(char s2[]){    int i=-1,j=0;    next[0]=-1;    int l=strlen(s2);    while(j<l)    {           if(i==-1||s2[i]==s2[j])           {               i++; j++;               if(s2[j]!=s2[i])               next[j]=i;               else next[j]=next[i];           }           else i=next[i];    }}void index_KMP(char s1[],char s2[]){    int i=0,j=0,len1=strlen(s1),len2=strlen(s2);    while((i<len1))    {        if(j==-1||s1[i]==s2[j]) {j++;i++;}        else j=next[j];    if(j==len2)    {        ans++;    }    }}int main(){    int n,i,p;    scanf("%d",&n);    while(n--)    {        ans=0;        scanf("%s%s",str1,str2);        get_next(str1);        index_KMP(str2,str1);        printf("%d\n",ans);    }    return 0;}

kmp模板

void get_next(char s2[]){    int i=-1,j=0;    next[0]=-1;    int l=strlen(s2);    while(j<l)    {           if(i==-1||s2[i]==s2[j])           {               i++; j++;               if(s2[j]!=s2[i])               next[j]=i;               else next[j]=next[i];           }           else i=next[i];    }}int index_KMP(char s1[],char s2[],int pos){    int i=pos,j=0,len1=strlen(s1),len2=strlen(s2);    while((i<len1)&&(j<len2))    {        if(j==-1||s1[i]==s2[j]) {j++;i++;}        else j=next[j];    }    if(j==len2)    return i-len2;    else return -1;}