Poj 3461 Oulipo
2016-01-31 15:53
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Oulipo
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 ***ERDXIVYERDIAN Sample Output 1 3 0 Source BAPC 2006 Qualification |
AC代码如下：
#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
const int maxn1=1000000+5;
const int maxn2=10000+5;
char aim[maxn1],tmp[maxn2];
int next[maxn2];
void getNext(int len){
int j=-1,i=0;
memset(next,0,sizeof(next));
next[0]=-1;
while(i<len){
if(j==-1 || tmp[i]==tmp[j]){
i++,j++;
next[i]=j;
}
else j=next[j];
}
}
void KMP(int len1,int len2){
int ans=0;
int j=0,i=0;
while(i<len2){
if(j==-1 || aim[i]==tmp[j]){
i++,j++;
if(j==len1){
ans++;
j=next[j];
}
}
else j=next[j];
}
printf("%d\n",ans);
}
int main(){
int t;
scanf("%d",&t);
while(t--){
scanf("%s",tmp);
scanf("%s",aim);
int len1=strlen(tmp);
int len2=strlen(aim);
getNext(len1);
KMP(len1,len2);
}
return 0;
}
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