SCU 4438

题目链接：

http://acm.scu.edu.cn/soj/problem.action?id=4438

题解：

变形kmp

代码：

#include 
#include 
#include 
#include 
#include 
using namespace std;
#define met(a,b) memset(a,b,sizeof(a))
#define inf 0x3f3f3f3f
typedef long long ll;
const int maxn = 5*1e6+10;
char s1[maxn],s2[maxn];
char name[maxn];
int nextt[maxn];
int pre[maxn];
int k;

void kmp_pre(char x[],int m,int next[])
{
    int i,j;
    j=next[0]=-1 ;
    i=0;
    while(i while(-1!=j && x[i]!=x[j])j=next[j];
        next[++ i]=++ j;
    }
}

void preKMP(char x[],int m,int kmpNext[])
{
    int i,j;
    j=kmpNext[0] =-1; i=0;
    while(iwhile(-1!=j && x[i]!=x[j])
            j=kmpNext[j];
        if(x[++ i]==x [++j] )
            kmpNext[ i]=kmpNext [j];
        else kmpNext[i]=j;
    }
}


void KMP_Count(char x[],int m,char y[],int n)
{//x是模式串,y是主串
    int i,j;
    met(name,'\0');
    met(pre,0);
    preKMP(x,m,nextt);
    kmp_pre(x,m,nextt);
    i=j=0;
    k=0;
    while(iwhile(-1!=j &&name[k]!=x[j])
            j=nextt[j];
        j++;
        k++;
        pre[k]=j;
        if(j>=m)
        {
            k-=m;
            j=pre[k];
        }
    }
}

int main()
{
    while (scanf("%s",s1)!=EOF)
    {
        scanf("%s",s2);
        int len1=strlen(s1);
        int len2=strlen(s2);
        KMP_Count(s1,len1,s2,len2);
//        printf("%s\n",name);
//        printf("%d\n",k);
        for(int i=0;iprintf("%c",name[i]);
        printf("\n");
    }
}