3620: 似乎在梦中见过的样子 KMP

枚举左端点跑KMP，O(n2)也能过真是！@#￥%……

#include<iostream>#include<cstdio>#include<cstring>using namespace std;int n,ans,k;char s[20005];int next[20005];inline void KMP(int p){    for (int i=1;i<=n;i++)        next[i]=p-1;    int j=p-1;    for (int i=p+1;i<=n;i++)    {        while (j!=p-1&&s[j+1]!=s[i]) j=next[j];        if (s[j+1]==s[i]) j++;        next[i]=j;    }    j=p-1;    for (int i=p+1;i<=n;i++)    {        while (j!=p-1&&s[j+1]!=s[i]) j=next[j];        if (s[j+1]==s[i]) j++;        while ((j-p+1)*2>=(i-p+1)) j=next[j];        if (j-p+1>=k) ans++;    }}int main(){    scanf("%s%d",s+1,&k);    n=strlen(s+1);    for (int i=1;i<=n;i++)        KMP(i);    cout << ans << endl;}