Oulipo
Time Limit: 3000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 19489 Accepted Submission(s): 7608
Problem 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.
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.
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
Source
KMP实现 140 ms
注意当找到一个时候 我们要让j=Next[j] 意思是从最长前缀直接跳过去 也就是向右移 减少右移次数
#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
const int MAX_N = 1000024;
int Next[MAX_N];
char mo[MAX_N],str[MAX_N];
int n1,n2,cnt;
void getnext(){
int i=0,j=-1;
while(i<n2){
if(j==-1||mo[i]==mo[j]) {
++i;
++j;
Next[i] = j;
}
else j = Next[j];
}
return ;
}
int kmp(){
int i=0,j=0;
while(i<n1){
if(j==-1||str[i]==mo[j])i++,j++;
else j=Next[j];
if(j==n2) {
j=Next[j];
cnt++;
}
}
return cnt;
}
int main(){
int t;
scanf("%d",&t);
while(t--){
cnt = 0;
memset(str,0,sizeof(str));
memset(mo,0,sizeof(mo));
scanf("%s",mo);
scanf("%s",str);
n2 = strlen(mo);
n1=strlen(str);
Next[0] = -1;
getnext();
printf("%d\n",kmp());
}
return 0;
}
拓展KMP实现 就不需要注意那个地方了
#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
const int MAX_N = 1000024;
int Next[MAX_N],ex[MAX_N];
char mo[MAX_N],str[MAX_N];
void getnext(char *str){
int i=0,j,po,len=strlen(str);
Next[0] = len;
while(str[i]==str[i+1]&&i+1<len)
i++;
Next[1] = i;
po = 1;
for(i=2;i<len;++i){
if(Next[i-po]+i<Next[po]+po)
Next[i] = Next[i-po];
else {
j = Next[po] + po -i;
if(j<0) j = 0;
while(i+j<len&&str[j]==str[j+i])
j++;
Next[i] = j;
po = i;
}
}
}
void exkmp(char *s1,char *s2){
int i=0,j,po,len = strlen(s1),l2=strlen(s2);
getnext(s2);
while(s1[i]==s2[i]&&i<l2&&i<len)
i++;
ex[0] = i;
po = 0;
for(i=1;i<len;++i){
if(Next[i-po]+i<ex[po]+po)
ex[i] = Next[i-po];
else {
j=ex[po]+po-i;
if(j<0) j = 0;
while(i+j<len&&j<l2&&s1[j+i]==s2[j])
j++;
ex[i]=j;
po=i;
}
}
}
int main(){
int t;
scanf("%d",&t);
while(t--){
int cnt = 0;
memset(str,0,sizeof(str));
memset(mo,0,sizeof(mo));
scanf("%s",mo);
scanf("%s",str);
exkmp(str,mo);
int len = strlen(str);
int m = strlen(mo);
for(int i=0;i<len;i++){
if(ex[i]==m) cnt++;
}
printf("%d\n",cnt);
}
return 0;
}