暴力处理每一个左端点，然后就和NOI2014动物园是差不多（几乎是一样的）
（一开始还以为是什么KMP的奇怪姿势）
1 #include<bits/stdc++.h> 2 #define N 1000005 3 #define LL long long 4 #define inf 0x3f3f3f3f 5 using namespace std; 6 inline int ra() 7 { 8 int x=0,f=1; char ch=getchar(); 9 while (ch<'0' || ch>'9') {if (ch=='-') f=-1; ch=getchar();} 10 while (ch>='0' && ch<='9') {x=x*10+ch-'0'; ch=getchar();} 11 return x*f; 12 } 13 int k,n,fail[N],ans; 14 char ch[N]; 15 int main() 16 { 17 scanf("%s",ch+1); k=ra(); 18 n=strlen(ch+1); 19 for (int i=1; i<=n-k*2; i++) 20 { 21 int fix=i-1; fail[i]=i-1; 22 for (int j=i+1; j<=n; j++) 23 { 24 while (ch[fix+1]!=ch[j] && fix>i-1) fix=fail[fix]; 25 if (ch[fix+1]==ch[j]) fix++; fail[j]=fix; 26 } 27 for (int j=i+k*2; j<=n; j++) 28 { 29 int pos=j; 30 while ((fail[pos]-i+1)*2>=j-i+1) 31 pos=fail[pos]; 32 if (fail[pos]-i+1>=k) ans++; 33 } 34 } 35 cout<<ans; 36 return 0; 37 }