#include <bits/stdc++.h> using namespace std; inline void extend(pair<int, int>& I, int i) { I.first = min(I.first, i); I.second = max(I.second, i); } inline int card(const pair<int, int>& I) { return I.second - I.first + 1; } void calc(int k, long long& cnt, const pair<int, int>& I, int n) { int d = k - card(I); if (d >= 0) { pair<int, int> I_sup = {max(0, I.first - d), min(n-1, I.second + d)}; cnt += card(I_sup) - k + 1; } } int main() { ios::sync_with_stdio(0); cin.tie(0); int n; cin >> n; vector<int> p_inv(n); for (int i = 0; i < n; ++i) { int a; cin >> a; p_inv[--a] = i; } long long cnt = 1; pair<int, int> I = {p_inv[n-1], p_inv[n-1]}; for (int m = n-2; m >= (n-1)/2; --m) { extend(I, p_inv[m]); int k = (n-m-1) << 1; calc(k, cnt, I, n); if (k+1 <= n) calc(k+1, cnt, I, n); } cout << 2*n + 1 << ' ' << cnt; }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 | #include <bits/stdc++.h> using namespace std; inline void extend(pair<int, int>& I, int i) { I.first = min(I.first, i); I.second = max(I.second, i); } inline int card(const pair<int, int>& I) { return I.second - I.first + 1; } void calc(int k, long long& cnt, const pair<int, int>& I, int n) { int d = k - card(I); if (d >= 0) { pair<int, int> I_sup = {max(0, I.first - d), min(n-1, I.second + d)}; cnt += card(I_sup) - k + 1; } } int main() { ios::sync_with_stdio(0); cin.tie(0); int n; cin >> n; vector<int> p_inv(n); for (int i = 0; i < n; ++i) { int a; cin >> a; p_inv[--a] = i; } long long cnt = 1; pair<int, int> I = {p_inv[n-1], p_inv[n-1]}; for (int m = n-2; m >= (n-1)/2; --m) { extend(I, p_inv[m]); int k = (n-m-1) << 1; calc(k, cnt, I, n); if (k+1 <= n) calc(k+1, cnt, I, n); } cout << 2*n + 1 << ' ' << cnt; } |