72 lines
2.2 KiB
C++
72 lines
2.2 KiB
C++
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////////////////////////////////////////////////////////////////////////////////////////////////
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// Andrey Odintsov
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#include <bits/stdc++.h>
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using namespace std;
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#define mp make_pair
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#define pb push_back
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#define FAST_IO ios_base::sync_with_stdio(false); cin.tie(0)
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#define FILE_IO(x) freopen((string(x) + ".in").c_str(), "r", stdin); freopen((string(x) + ".out").c_str(), "w", stdout)
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#define sz(x) ((int)((x).size()))
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#define len(x) ((int)((x).length()))
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#define x first
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#define y second
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#define foreach(it, v) for (auto it : v)
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#define rep(it, n) for (int it = 0; it < n; ++it)
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#define forin(it, l, r) for (int it = l; it < r; ++it)
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#define all(x) x.begin(), x.end()
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typedef long long ll;
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typedef unsigned long long ull;
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typedef long double ld;
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typedef pair<int, int> pii;
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typedef pair<ll, ll> pll;
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const int INF = (1 << 31) - 1;
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const ll LINF = (1ll << 63) - 1;
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const double DINF = numeric_limits<double>::infinity();
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const int MOD = 1e9 + 7;
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const double EPS = 1e-7;
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ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
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mt19937 mmtw(MOD);
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ll rnd(ll x, ll y) { static uniform_int_distribution<ll> d; return d(mmtw) % (y - x + 1) + x; }
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template <class T> T arr_max(T a[], int n) { T res = a[0]; for (int i = 1; i < n; ++i) if (a[i] > res) res = a[i]; return res; }
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template <class T> T arr_min(T a[], int n) { T res = a[0]; for (int i = 1; i < n; ++i) if (a[i] < res) res = a[i]; return res; }
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template <class T> T binpow(T n, T k) { if (k == 1) return n; if (k & 1) return binpow(n, k - 1) * n; T a = binpow(n, k / 2); return a * a; }
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template <class T> T fact(T n) { if (n == 1) return 1; return n * fact(n - 1); }
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////////////////////////////////////////////////////////////////////////////////////////////////
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const int MAXN = 25;
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ll n;
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ll a[MAXN];
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ll res;
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vector <ll> not_used;
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int main() {
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cin >> n;
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rep(i, n) {
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cin >> a[i];
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}
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if (n == 1) {
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cout << 1 << endl;
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return 0;
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}
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for (int i = 1; i <= n; ++i) {
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not_used.push_back(i);
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}
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ll size = fact(n - 1);
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rep(i, n) {
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auto it = find(all(not_used), a[i]);
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res += size * (it - not_used.begin());
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not_used.erase(it);
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if (i != n - 1) {
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size = size / (n - i - 1);
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}
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}
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cout << res + 1 << endl;
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return 0;
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} |