```cpp
#include <bits/stdc++.h>
using namespace std;
class Samfun {
protected:
enum { lettersetsize = 26,
maxsize = 1000000 };
#define foreach for (int i = 0; i < cnt; i++)
#define foreach1 for (int i = 1; i < cnt; i++)
#define foreachletter for (int i = 0; i < lettersetsize; i++)
#define modify -'a'
#define modified -= 'a'
public:
struct node {
int len, link, next[26], firstpos, endpos, id;
bool isfinal = false;
node(int l = 0, int k = 0, int *n = nullptr, int f = 0, int d = -1) {
len = l, link = k, firstpos = f, endpos = 0, id = d;
if (n == nullptr)
memset(next, 0, sizeof next);
else
foreachletter next[i] = n[i];
}
node(const node &n) {
len = n.len, link = n.link, firstpos = n.firstpos, endpos = n.endpos, id = n.id;
foreachletter next[i] = n.next[i];
}
};
protected:
node value[maxsize << 1];
int cnt = 0, last = 0;
#define len(x) (value[(x)].len)
#define link(x) (value[(x)].link)
#define linkto(x, y) (link(x) = (y))
#define next(x) (value[(x)].next)
#define nextat(x, y) (next(x)[(y)])
#define nextto(x, y, z) (nextat(x, y) = (z))
#define fir(x) (value[(x)].firstpos)
#define endpos(x) (value[(x)].endpos)
#define id(x) (value[(x)].id)
#define final(x) (value[(x)].isfinal)
#define update(x) (x = link(x))
#define at(x) (value[(x)])
#define root 0
inline int newnode(int l = 0, int k = 0, int *n = nullptr, int f = 0) {
value[cnt] = node(l, k, n, f, cnt);
return cnt++;
}
public:
Samfun() { newnode(0, -1); }
int push_back(char ch) {
ch modified;
int now = newnode(len(last) + 1, 0, nullptr, len(last)), father = last;
for (father; ~father && !nextat(father, ch); nextto(father, ch, now), update(father))
;
if (~father) {
int son = nextat(father, ch);
if (len(son) == len(father) + 1)
linkto(now, son);
else {
int copy = newnode(len(father) + 1, link(son), next(son), fir(son));
for (father; ~father && nextat(father, ch) == son; nextto(father, ch, copy), update(father))
;
linkto(now, copy), linkto(son, copy);
}
}
return last = now, final(now) = true, endpos(now) = 1, cnt;
}
int push_back(string s) {
for (auto i : s)
push_back(i);
return cnt;
}
bool is_in(string s) {
for (int i = 0, j = 0; i < s.size(); j = nextat(j, s[i++] modify))
if (!nextat(j, s[i] modify))
return false;
return true;
}
int longest_prefix_in(string s) {
int ans = 0;
for (int i = 0, j = 0; i < s.size(); j = nextat(j, s[i++] modify), ans++)
if (!nextat(j, s[i] modify))
return ans;
return ans;
}
int first_in(string s) {
int ans = 0, j = 0;
for (int i = 0; i < s.size(); j = nextat(j, s[i++] modify), ans++)
if (!nextat(j, s[i] modify))
return -1;
return fir(j) - s.size() + 1;
}
int substr_count() {
int ans = 0;
foreach1
ans += len(i) - len(link(i));
return ans;
}
int substr_lensum() {
int ans = 0;
foreach1
ans += len(i) * (len(i) + 1) / 2 - len(link(i)) * (len(link(i)) + 1) / 2;
return ans;
}
int dfs_endpos() {
node sv[cnt];
foreach
sv[i] = at(i);
sort(sv, sv + cnt, [](node &a, node &b) { return a.len > b.len; });
foreach
sv[i].id ? (endpos(link(sv[i].id)) += endpos(sv[i].id)) : 0;
}
int ep(int x) { return endpos(x); }
int in_times(string s) {
int ans = 0, j = 0;
for (int i = 0; i < s.size(); j = nextat(j, s[i++] modify), ans++)
if (!nextat(j, s[i] modify))
return 0;
return endpos(j);
}
int P3804() {
int ans = 0;
foreach1
ans = max(ans, endpos(i) * len(i));
return ans;
}
};
int main() {
Samfun a;
string s;
cin >> s;
a.push_back(s);
a.dfs_endpos();
cout << a.P3804() << endl;
}
```
by TensorFlow_js @ 2022-07-03 20:09:23
另：`出现次数不为 1` 还未加上。
by TensorFlow_js @ 2022-07-03 20:11:36
@[Suruka](/user/321566) 毒氧，正常现象
by Lai_Da_Ji @ 2022-07-03 20:12:33
@[dpkajj](/user/515930) 这题强制开 O2 
by TensorFlow_js @ 2022-07-03 20:12:55
@[Suruka](/user/321566) 可以试试把内存压一压
by Lai_Da_Ji @ 2022-07-03 20:14:20
@[dpkajj](/user/515930) `Runtime Error.
Received signal 7: Bus error (bad memory access).`
by TensorFlow_js @ 2022-07-03 20:17:08
@[Suruka](/user/321566) 对不起，我不太擅长处理这种问题，你可以另请高人
@[S11EDG](/user/186045)
by Lai_Da_Ji @ 2022-07-03 20:21:41
oK
by TensorFlow_js @ 2022-07-03 20:23:11
@[dpkajj](/user/515930) 别说正常现象了，到时候到 NOI 决定命运的时候就爆零了
by liqingyang @ 2022-07-03 20:23:21
@[Suruka](/user/321566) 提供几种可能：函数有非void返回值但最终没有return，变量不是全局但没赋初值
by liqingyang @ 2022-07-03 20:26:41