貌似粘错代码了
```cpp
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 300000 + 5;
struct PAM
{
int nxt[maxn][26], link[maxn], len[maxn], size[maxn], sz, last;
int s[maxn];
void inline extend(int c, int now)
{
int p = last;
while(s[now - len[p] - 1] != s[now]) p = link[p];
if(!nxt[p][c]) {
int q = link[p];
while(s[now - len[q] - 1] != s[now]) q = link[q];
link[++sz] = nxt[q][c], nxt[p][c] = sz, len[sz] = len[p] + 2;
}
last = nxt[p][c]; ++size[last];
}
void inline build(char *str)
{
for(int i = 0; str[i]; ++i) s[i + 1] = str[i] - 'a';
link[0] = link[1] = 1; len[0] = 0, len[1] = -1;
sz = 1;
for(int i = 0; str[i]; ++i) extend(s[i + 1], i + 1);
for(int i = sz; i > 1; --i) size[link[i]] += size[i];
}
} pam;
char str[maxn];
void inline Solve()
{
ll ans = 0;
pam.build(str);
for(int i = 2; i <= pam.sz; ++i) ans = max(ans, (ll)pam.size[i] * pam.len[i]);
printf("%lld\n", ans);
}
int main()
{
scanf("%s", str);
Solve();
return 0;
}
```
by 星野梦美 @ 2018-12-15 23:47:36
已解决。
"0" 有 “空” 与 “a” 的二义性，不处理这部分不行
其实这玩意就能卡掉：
```
a
```
by 星野梦美 @ 2018-12-15 23:54:38