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| #include <cstdio>
#include <cassert>
#include <cstring>
#include <algorithm>
#include <utility>
#include <vector>
using namespace std;
using ll = long long;
const int maxn = 100000 + 5;
namespace SA {
const int L = 18;
int n, m, sa[maxn], h[maxn], c[maxn], x[maxn], y[maxn];
int dp[L][maxn];
void rsort() {
for (int i = 1; i <= m; i++) c[i] = 0;
for (int i = 1; i <= n; i++) c[x[i]]++;
for (int i = 1; i <= m; i++) c[i] += c[i - 1];
for (int i = n; i >= 1; i--) sa[c[x[y[i]]]--] = y[i];
}
int cmp(int i, int j, int k) {
int a = i + k > n ? -1 : y[i + k];
int b = j + k > n ? -1 : y[j + k];
return y[i] == y[j] && a == b;
}
void build(int nn, int* s) {
n = nn; m = nn + 1;
for (int i = 1; i <= n; i++) x[i] = s[i], y[i] = i;
rsort();
for (int k = 1, p; k <= n; k += k, m = p) {
p = 0;
for (int i = n; i > n - k; i--) y[++p] = i;
for (int i = 1; i <= n; i++) if (sa[i] > k) y[++p] = sa[i] - k;
rsort();
for (int i = 1; i <= n; i++) swap(x[i], y[i]);
x[sa[1]] = p = 1;
for (int i = 2; i <= n; i++) x[sa[i]] = cmp(sa[i], sa[i - 1], k) ? p : ++p;
}
for (int i = 1; i <= n; i++) x[sa[i]] = i;
for (int i = 1, k = 0; i <= n; i++) {
if (k) k--;
int j = sa[x[i] - 1];
while (i + k <= n && j + k <= n && s[i + k] == s[j + k]) k++;
h[x[i]] = k;
}
for (int i = 1; i <= n; i++) dp[0][i] = h[i];
for (int j = 1; j < L; j++) {
for (int i = 1; i + (1 << j) <= n + 1; i++) {
dp[j][i] = min(dp[j - 1][i], dp[j - 1][i + (1 << (j - 1))]);
}
}
}
int qlcp(int l, int r) {
if (l <= 0 || l > n) return 0;
if (r <= 0 || r > n) return 0;
if (l == r) return n - l + 1;
l = x[l]; r = x[r];
if (l > r) swap(l, r);
l++; int k = __lg(r - l + 1);
return min(dp[k][l], dp[k][r - (1 << k) + 1]);
}
}
int n, a[maxn], ord[maxn];
int ch[maxn][26], nxt[maxn][26];
char s[maxn];
int lcp(int x, int y) {
int Bx = x, By = y;
int len = 0;
x--; y--;
for (int j = 0; j < 26 && x + 1 <= n && y + 1 <= n; j++) {
int l = SA::qlcp(x + 1, y + 1);
if (x + 1 + l < nxt[Bx][j] && y + 1 + l < nxt[By][j]) {
return len + l;
}
if (nxt[Bx][j] - Bx == nxt[By][j] - By) {
len += nxt[Bx][j] - x;
x = nxt[Bx][j];
y = nxt[By][j];
} else if (nxt[Bx][j] - Bx < nxt[By][j] - By) {
return len + nxt[Bx][j] - x - 1;
} else {
return len + nxt[By][j] - y - 1;
}
}
return len + SA::qlcp(x + 1, y + 1);
}
int main() {
scanf("%d%s", &n, s + 1);
vector<int> last(26, -1);
for (int i = 1; i <= n; i++) {
ord[i] = i;
int ch = s[i] - 'a';
if (last[ch] == -1) {
a[i] = n + 1;
} else {
a[i] = i - last[ch];
}
last[ch] = i;
}
SA::build(n, a);
for (int j = 0; j < 26; j++) {
nxt[n + 1][j] = n + n + n;
ch[n + 1][j] = n + n + n;
}
for (int i = n; i >= 1; i--) {
memcpy(nxt[i], nxt[i + 1], sizeof nxt[i + 1]);
nxt[i][s[i] - 'a'] = i;
}
for (int i = n; i >= 1; i--) {
memcpy(ch[i], nxt[i], sizeof nxt[i]);
sort(nxt[i], nxt[i] + 26);
}
sort(ord + 1, ord + 1 + n, [&](int x, int y) {
int len = lcp(x, y);
if (x + len > n || y + len > n) {
return x + len > n;
}
int chX = a[x + len], chY = a[y + len];
for (int j = 0; j < 26; j++) {
if (ch[x][j] == x + len) {
chX = 0;
break;
}
}
for (int j = 0; j < 26; j++) {
if (ch[y][j] == y + len) {
chY = 0;
break;
}
}
return chX < chY;
});
ll ans = 1ll * n * (n + 1) / 2;
for (int i = 1; i < n; i++) {
ans -= lcp(ord[i], ord[i + 1]);
}
printf("%lld\n", ans);
return 0;
}
|
