0
1
mirror of https://git.sb/baoshuo/OI-codes.git synced 2024-12-13 05:46:26 +00:00
OI-codes/Luogu/P1494/P1494.cpp

78 lines
1.6 KiB
C++

#include <iostream>
#include <algorithm>
#include <cmath>
#include <tuple>
#include <vector>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 50005;
int n, m, a[N], c[N], t;
std::pair<long long, long long> now, ans[N];
std::vector<std::tuple<int, int, int>> q;
void add(int x) {
if (++c[x] > 1) {
now.first += c[x] * (c[x] - 1) - (c[x] - 1) * (c[x] - 2);
}
}
void del(int x) {
if (--c[x]) {
now.first += c[x] * (c[x] - 1) - (c[x] + 1) * c[x];
}
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m;
t = sqrt(n);
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
for (int i = 1, l, r; i <= m; i++) {
cin >> l >> r;
q.push_back(std::make_tuple(i, l, r));
}
std::sort(q.begin(), q.end(), [&](auto a, auto b) {
int p = std::get<1>(a) / t,
q = std::get<1>(b) / t;
return p == q ? std::get<2>(a) < std::get<2>(b) : p < q;
});
int i = 0, j = 1, x, l, r;
for (auto e : q) {
std::tie(x, l, r) = e;
if (l == r) {
ans[x] = std::make_pair(0, 1);
} else {
while (i < r) add(a[++i]);
while (i > r) del(a[i--]);
while (j < l) del(a[j++]);
while (j > l) add(a[--j]);
now.second = 1ll * (r - l + 1) * (r - l);
int g = std::__gcd(now.first, now.second);
ans[x] = std::make_pair(now.first / g, now.second / g);
}
}
for (int i = 1; i <= m; i++) {
cout << ans[i].first << '/' << ans[i].second << endl;
}
return 0;
}