#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; } |
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