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.
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.
3 BAPC BAPC AZA AZAZAZA VERDI AVERDXIVYERDIAN
1 3 0
直接套用kmp算法,统计匹配的个数即可
code:
#include <iostream> #include <cstdio> #include <cstring> using namespace std; int Next[100000]; char w[100000],t[10000000]; void getNext(){//求next数组的函数 int i = -1,j = 0;//两个下标错开 Next[0] = -1;//初始化next[0]=-1 int lenw = strlen(w); while(j < lenw){ if(i==-1||w[i]==w[j]){ i++,j++;//相等或i=-1,ij同时加 if(w[i]==w[j])Next[j] = Next[i];//这一步是个优化,如果相同等于这个相同这个点i的next[i] else Next[j] = i;//不同直接等于i } else i = Next[i];//不同从next[i]开始匹配 } return; } int Kmp(){ int cnt = 0; int i = 0,j = 0; int lenw = strlen(w); int lent = strlen(t); getNext();//得到next数组 while(j < lent){ if(i==-1||w[i]==t[j]){ i++,j++;//类似于getnext函数 if(i==lenw){ cnt++;//如果模式字符串到了末尾个数++,可以不用对i进行操作i会通过next数组自己初始回去 } } else i = Next[i]; } return cnt; } int main(){ int num; scanf("%d",&num); while(num--){ scanf("%s%s",w,t); printf("%d\n",Kmp()); } return 0; }