hihoCoder 1015 KMP算法

http://hihocoder.com/problemset/problem/1015

因为kmp算法只预处理b串,因而适合求解,给定一个串和一群不同的a串,问b是那些a串的子串.

或者查找模式串在原串出现了几次.

#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <string>
#include <algorithm>
#include <string>
#include <set>
#include <functional>
#include <numeric>
#include <sstream>
#include <stack>
#include <map>
#include <queue>
#pragma comment(linker, "/STACK:102400000,102400000")
#define CL(arr, val)    memset(arr, val, sizeof(arr))

#define ll long long
#define inf 0x7f7f7f7f
#define lc l,m,rt<<1
#define rc m + 1,r,rt<<1|1
#define pi acos(-1.0)

#define L(x)    (x) << 1
#define R(x)    (x) << 1 | 1
#define MID(l, r)   (l + r) >> 1
#define Min(x, y)   (x) < (y) ? (x) : (y)
#define Max(x, y)   (x) < (y) ? (y) : (x)
#define E(x)        (1 << (x))
#define iabs(x)     (x) < 0 ? -(x) : (x)
#define OUT(x)  printf("%I64d\n", x)
#define lowbit(x)   (x)&(-x)
#define Read()  freopen("a.txt", "r", stdin)
#define Write() freopen("b.txt", "w", stdout);
#define maxn 1000000000
#define N 2510
#define mod 1000000000
using namespace std;

int p[10010];
char s1[10010],s2[1000010];
int n,m;
void next(int m)
{
int j=0;
p[1]=0;
for(int i=2;i<=m;i++)
{
while(j>0&&(s1[j+1]!=s1[i])) j=p[j];
if(s1[j+1]==s1[i]) j+=1;
p[i]=j;
//printf("%d\n",p[i]);
}
}

int kmp(int n)
{
int j=0,k=0;
for(int i=1;i<=n;i++)
{
while(j>0&&s1[j+1]!=s2[i]) j=p[j];
if(s1[j+1]==s2[i]) j=j+1;
if(j==m)
{
k++;
j=p[j];
}
//printf("%d\n",j);
}
return k;
}
int main()
{
// freopen("a.txt","r",stdin);
int k;
scanf("%d",&k);
for(int i=0;i<k;i++)
{
scanf("%s",s1+1);
scanf("%s",s2+1);
m=strlen(s1+1);
//printf("%d\n",m);
next(m);
n=strlen(s2+1);
printf("%d\n",kmp(n));
}
return 0;
}