#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
typedef long long ll;
using namespace __gnu_pbds;
using namespace std;
template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n; cin >> n;
vector<int> a(n);
for(int i=0; i<n; ++i) cin >> a[i];
stack<int> stos;
auto dozuc = [&](int x) {
while(stos.size() && stos.top() <= x) stos.pop();
stos.push(x);
};
for(int i=n-1; i>=0; --i) {
dozuc(a[i]);
}
int ans = stos.size();
for(int i=n-1; i>0; --i) {
dozuc(a[i]);
ans = max(ans, (int)stos.size());
}
cout << ans << "\n";
return 0;
}
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 | #include <bits/stdc++.h> #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> typedef long long ll; using namespace __gnu_pbds; using namespace std; template <typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>; int main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); int n; cin >> n; vector<int> a(n); for(int i=0; i<n; ++i) cin >> a[i]; stack<int> stos; auto dozuc = [&](int x) { while(stos.size() && stos.top() <= x) stos.pop(); stos.push(x); }; for(int i=n-1; i>=0; --i) { dozuc(a[i]); } int ans = stos.size(); for(int i=n-1; i>0; --i) { dozuc(a[i]); ans = max(ans, (int)stos.size()); } cout << ans << "\n"; return 0; } |
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