Oulipo poj 3461 KMP连续匹配（有重合）

Oulipo

Time Limit:1000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u

Submit  Status

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

蓝桥杯失利后的第一水，KMP连续匹配，匹配成功后让j=next[j]就可以继续匹配，此时是有覆盖的情况，如果要考虑没有覆盖的，直接让j=0，i=i+j就行了。

#include <iostream>
#include <cmath>
#include <stdio.h>
#include <string>
#include <cstring>
#include <map>
#include <set>
#include <vector>
#include <stack>
#include <queue>
#include <iomanip>
#include <algorithm>
#define MAXN 1000010
using namespace std;

int nxt[MAXN];
char w[MAXN];
char t[MAXN];

void getnext(char x[],int len)
{
        int i,j;
        i=0;
        j=nxt[0]=-1;
        while(i<len)
        {
                while(j!=-1&&x[i]!=x[j]) j=nxt[j];
                if(x[++i]==x[++j]) nxt[i]=nxt[j];
                else nxt[i]=j;
        }
}

int kmp(char x[],char y[])
{
        int i,j;
        int ans=0;
        int m=strlen(x);
        int n=strlen(y);
        getnext(x,m);
        i=j=0;
        while(i<n)
        {
                while(j!=-1&&y[i]!=x[j]) j=nxt[j];
                i++;j++;
                if(j>=m)
                {
                        ans++;
                        j=nxt[j];
                }
        }
        return ans;
}



int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
            scanf("%s%s",w,t);
            printf("%d\n",kmp(w,t));
    }
    return 0;
}