hiho 1015 KMP

input

1<=T<=20

string1 1<=strlen(string1)<=1e4

string2 2<=strlen(string2)<=1e6

output

string1在string2出现的次数

在第i位不匹配时跳到idx[i-1]位继续匹配

 #include <cstdio>
 #include <queue>
 #include <cstring>
 #include <iostream>
 #include <cstdlib>
 #include <algorithm>
 #include <vector>
 #include <map>
 #include <set>
 #include <ctime>
 #include <cmath>

 using namespace std;

 const int N=1e6+;
 int idx[N],T;
 char a[N],b[];

 void Next()
 {
     idx[]=;
     for(int i=,j=;b[i];i++)
     {
         while(j&&b[i]!=b[j])
             j=idx[j-];
         b[i]==b[j]?idx[i]=++j:idx[i]=j;
     }
 }

 int kmp()
 {
     int c=,i,j;
     for(i=,j=;a[i];i++)
     {
         if(!b[j]) c++;
         if(a[i]!=b[j])
         {
             while(j)
             {
                 j=idx[j-];
                 if(b[j]==a[i])
                 {
                     j++;
                     break;
                 }
             }
         }
         else j++;
     }
     if(!b[j]) c++;
     return c;
 }

 int main()
 {
     //freopen("/home/user/桌面/in","r",stdin);
     scanf("%d",&T);
     while(T--)
     {
         scanf("%s%s",b,a);
         Next();
         //for(int i=0;b[i];i++) printf("%d ",idx[i]);printf("\n");
         printf("%d\n",kmp());
     }
     //printf("time=%.3lf",(double)clock()/CLOCKS_PER_SEC);
     return ;
 }