P3804 【模板】后缀自动机
1 #include <bits/stdc++.h>
2 using namespace std;
3 const int maxn = 2e6+5;
4 typedef long long ll;
5 char s[maxn];
6 int a[maxn], c[maxn], size[maxn], n;
7 ll ans = 0;
8 struct SuffixAutoMaton {
9 int last, cnt;
10 int ch[maxn*2][26], fa[maxn*2], len[maxn*2];
11 void ins(int c) {
12 int p = last, np = ++cnt;
13 last = np; len[np] = len[p]+1;
14 for (;p && !ch[p][c]; p = fa[p]) ch[p][c] = np;
15 if (!p) fa[np] = 1;
16 else {
17 int q = ch[p][c];
18 if (len[p]+1 == len[q]) fa[np] = q;
19 else {
20 int nq = ++cnt;
21 len[nq] = len[p]+1;
22 memcpy(ch[nq],ch[q],sizeof(ch[q]));
23 fa[nq] = fa[q]; fa[q] = fa[np] = nq;
24 for (; ch[p][c] == q; p = fa[p]) ch[p][c] = nq;
25 }
26 }
27 size[np] = 1;
28 }
29 void build() {
30 scanf("%s",s+1);
31 int lens = strlen(s+1);
32 last = cnt = 1;
33 for (int i = 1; i <= lens; i++) ins(s[i]-'a');
34 }
35 void solve() {
36 for (int i = 1; i <= cnt; i++) c[len[i]]++;
37 for (int i = 1; i <= cnt; i++) c[i] += c[i-1];
38 for (int i = 1; i <= cnt; i++) a[c[len[i]]--] = i;
39 for (int i = cnt; i; i--) {
40 int p = a[i];
41 size[fa[p]] += size[p];
42 if (size[p] > 1) ans = max(ans, 1LL*size[p]*len[p]);
43 }
44 printf("%lld\n",ans);
45 }
46 }sam;
47 int main() {
48 sam.build();
49 sam.solve();
50 return 0;
51 }
