kmp算法基础

https://www.luogu.com.cn/problemnew/solution/P3375

 #include<bits/stdc++.h>
 using namespace std;
 const int maxn=1e6+;
 int kmp[maxn];
 char a[maxn],b[maxn];
 int main()
 {
     scanf("%s%s",a+,b+);
     int lena=strlen(a+);
     int lenb=strlen(b+);
     int index=;
     for(int i=;i<=lenb;i++){
         while(index&&b[i]!=b[index+])
             index=kmp[index];
         if(b[index+]==b[i]) index++;
         kmp[i]=index;
     }
     index=;
     for(int i=;i<=lena;i++){
         while(index>&&b[index+]!=a[i])
             index=kmp[index];
         if(b[index+]==a[i])
            index++;
         if(index==lenb) {cout<<i-lenb+<<endl;index=kmp[index];}
     }
     for(int i=;i<=lenb;i++)
         printf("%d ",kmp[i]);
     printf("\n");
 }