poj 3461 Oulipo kmp
| Time Limit: 1000MS | Memory Limit: 65536K | |
| Total Submissions: 26252 | Accepted: 10478 |
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
3 BAPC BAPC AZA AZAZAZA VERDI AVERDXIVYERDIAN
Sample Output
1 3 0
这道题就是给你一个模式串，给你个主串，然后问你出现多少次
直接kmp搞一发就好
//qscqesze #include <cstdio> #include <cmath> #include <cstring> #include <ctime> #include <iostream> #include <algorithm> #include <set> #include <vector> #include <sstream> #include <queue> #include <typeinfo> #include <fstream> #include <map> typedef long long ll; using namespace std; //freopen("D.in","r",stdin); //freopen("D.out","w",stdout); #define sspeed ios_base::sync_with_stdio(0);cin.tie(0) #define maxn 100001 #define eps 1e-9 const int inf=0x7fffffff; //无限大 void kmp_pre(char x[],int m,int next[]) { int i,j; j=next[0]=-1; i=0; while(i<m) { while(-1!=j&&x[i]!=x[j])j=next[j]; next[++i]=++j; } } int next[maxn]; int Kmp_count(char x[],int m,char y[],int n) { int i,j; int ans=0; //preKmp(x,m,next); kmp_pre(x,m,next); i=j=0; while(i<n) { while(-1!=j&&y[i]!=x[j])j=next[j]; i++;j++; if(j>=m) { ans++; j=next[j]; } } return ans; } int main() { int t; cin>>t; while(t--) { char a[maxn]; char b[1000001]; scanf("%s%s",a,b); int n=strlen(a); int m=strlen(b); printf("%d\n",Kmp_count(a,n,b,m)); } }
贴上另外一个傻逼代码，这个代码T了……
用的是STL里面的strstr()
这个STL的用处是来找到主串中，第一个出现的地址，否则的话，就返回NULL
//qscqesze #include <cstdio> #include <cmath> #include <cstring> #include <ctime> #include <iostream> #include <algorithm> #include <set> #include <vector> #include <sstream> #include <queue> #include <typeinfo> #include <fstream> #include <map> typedef long long ll; using namespace std; //freopen("D.in","r",stdin); //freopen("D.out","w",stdout); #define sspeed ios_base::sync_with_stdio(0);cin.tie(0) #define maxn 100001 #define eps 1e-9 const int inf=0x7fffffff; //无限大 char a[maxn*10]; char b[maxn*10]; int main() { int t; cin>>t; while(t--) { scanf("%s%s",a,b); int ans=0; while(strstr(b,a)!=NULL) { int k=strstr(b,a)-b; ans++; b[k]='*'; } printf("%d\n",ans); } }
