hdu 4300 Clairewd’s message (KMP)

# include <stdio.h>
# include <algorithm>
# include <string.h>
using namespace std;
int len;
int next[100010];
char a1[100010],a2[100010],a3[100010];
void Getnext()
{
int i=0,j=-1;
next[0]=-1;
while(i<len)
{
if(j==-1||a2[j]==a2[i])
i++,j++,next[i]=j;
else
j=next[j];
}
}
int KMP()
{
int len1=strlen(a3);
int len2=strlen(a2);
int i=0,j=0;
while(i<len1&&j<len2)
{
if(j==-1||a2[j]==a3[i])
{
i++;j++;
if(i==len1)
return j;
}
else
j=next[j];
}
return 0;

}
int main()
{
int i,j,t;
while(~scanf("%d",&t))
{
while(t--)
{
scanf("%s %s",a1,a2);
printf("%s",a2);
len=strlen(a2);
strcpy(a3,a2+(len+1)/2);
for(i=0;a2[i];i++)//转化为加密串
{
for(j=0;j<26;j++)
{
if(a2[i]==a1[j])
{
a2[i]='a'+j;
break;
}
}
}
for(i=0;a2[i];i++)
printf("%c",a2[i]);
Getnext();//a2

int flag=KMP();//a3,a2
for(i=flag;i<len-flag;i++)
printf("%c",a2[i]);
printf("\n");

}
}
return 0;
}