Oulipo_poj3461_kmp

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.

题意

给出t对字符串，求a串在b串中的出现次数

题解

直接作t次kmp，求匹配数

不要问我为什么用p，c++字符串太蛋疼

Code

var  p:array[1..100000]of longint;  t:longint;function kmp(var a,b:ansistring):longint;var  i,j,n,m:longint;begin  n:=length(a);  m:=length(b);  j:=0;  kmp:=0;  for i:=1 to n do  begin    while (a[i]<>b[j+1])and(j>0) do j:=p[j];    if (a[i]=b[j+1]) then      inc(j);    if (j=m) then      begin        inc(kmp);        j:=p[j];      end;  end;end;procedure init;var  i,j,v,n,m:longint;  a,b:ansistring;begin  readln(t);  for v:=1 to t do  begin    readln(b);    readln(a);    m:=length(b);    fillchar(p,sizeof(p),0);    p[1]:=0;    j:=0;    for i:=2 to m do    begin      while (b[i]<>b[j+1])and(j>0) do j:=p[j];      if (b[i]=b[j+1]) then        inc(j);      p[i]:=j;    end;    writeln(kmp(a,b));  end;end;begin  init;end.