// {{{
#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define each(...) for (auto& __VA_ARGS__)
#define rep(i, b, e) for (int i = (b); i <= (e); i++)
#define rev(i, b, e) for (int i = (e); i >= (b); i--)
#define mp make_pair
#define mt make_tuple
#define x first
#define y second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define endl '\n'
#define tC template<class
#define $(x) #x<<'='<<(x)<<' '
using namespace std;
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using vb = vector<bool>;
using vi = vector<int>;
using vl = vector<ll>;
using vs = vector<string>;
using vpi = vector<pii>;
using vpl = vector<pll>;
using vvi = vector<vi>;
using vvl = vector<vl>;
tC T, class C=greater<T>> using min_priority_queue = priority_queue<T,vector<T>,C>;
tC T> int sz(const T& a) { return (int)a.size(); }
tC T> bool amin(T& a, T b) { return b < a ? a = b, 1 : 0; }
tC T> bool amax(T& a, T b) { return b > a ? a = b, 1 : 0; }
const int oo = 1e9+1;
const ll OO = ll(1e18)+1;
auto now() { return chrono::high_resolution_clock::now().time_since_epoch().count(); }
mt19937 rnd(4488);
tC T> T rand(T lo, T hi) { return uniform_int_distribution<T>{lo,hi}(rnd); }
struct Debug {
#ifdef SPONGE
tC T>Debug operator<<(const T& x) { cerr<<"\033[1;33m"<<x<<"\033[0m"; return *this; }
#else
tC T>Debug operator<<(const T&) { return *this; }
#endif
} dbg;
namespace { void solve(); }
// }}}
int main()
{
//freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.precision(15);
cout.setf(ios::fixed,ios::floatfield);
cerr.precision(15);
cerr.setf(ios::fixed,ios::floatfield);
//rnd.seed(now());
int t=1;
//cin>>t;
rep(i,1,t){
//cout<<"Case #"<<i<<": ";
solve();
}
}
namespace {
const int MAX=1'000'005;
int n,a[MAX],dp[MAX];
vi pref,stos;
void solve()
{
cin>>n;
rep(i,1,n) cin>>a[i];
pref.pb(1);
rep(i,2,n) if(a[pref.back()]<a[i]) pref.pb(i);
rev(i,1,n){
while(sz(stos)>0 && a[i]>=a[stos.back()]) stos.pop_back();
stos.pb(i);
dp[i]=sz(stos);
}
int curr=0,ans=0;
rev(i,1,n){
amax(curr,a[i]);
if(pref.back()==i) pref.pop_back();
amax(ans,dp[i]);
int l=0,r=sz(pref)-1;
while(l<=r){
int mid=(l+r)/2;
if(curr<a[pref[mid]]){
amax(ans,dp[i]+sz(pref)-mid);
r=mid-1;
}
else{
l=mid+1;
}
}
}
cout<<ans<<endl;
}
}
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 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 | // {{{ #define _USE_MATH_DEFINES #include <bits/stdc++.h> #define each(...) for (auto& __VA_ARGS__) #define rep(i, b, e) for (int i = (b); i <= (e); i++) #define rev(i, b, e) for (int i = (e); i >= (b); i--) #define mp make_pair #define mt make_tuple #define x first #define y second #define pb push_back #define all(x) (x).begin(), (x).end() #define endl '\n' #define tC template<class #define $(x) #x<<'='<<(x)<<' ' using namespace std; using ll = long long; using pii = pair<int,int>; using pll = pair<ll,ll>; using vb = vector<bool>; using vi = vector<int>; using vl = vector<ll>; using vs = vector<string>; using vpi = vector<pii>; using vpl = vector<pll>; using vvi = vector<vi>; using vvl = vector<vl>; tC T, class C=greater<T>> using min_priority_queue = priority_queue<T,vector<T>,C>; tC T> int sz(const T& a) { return (int)a.size(); } tC T> bool amin(T& a, T b) { return b < a ? a = b, 1 : 0; } tC T> bool amax(T& a, T b) { return b > a ? a = b, 1 : 0; } const int oo = 1e9+1; const ll OO = ll(1e18)+1; auto now() { return chrono::high_resolution_clock::now().time_since_epoch().count(); } mt19937 rnd(4488); tC T> T rand(T lo, T hi) { return uniform_int_distribution<T>{lo,hi}(rnd); } struct Debug { #ifdef SPONGE tC T>Debug operator<<(const T& x) { cerr<<"\033[1;33m"<<x<<"\033[0m"; return *this; } #else tC T>Debug operator<<(const T&) { return *this; } #endif } dbg; namespace { void solve(); } // }}} int main() { //freopen("input.txt","r",stdin); //freopen("output.txt","w",stdout); ios_base::sync_with_stdio(0); cin.tie(0); cout.precision(15); cout.setf(ios::fixed,ios::floatfield); cerr.precision(15); cerr.setf(ios::fixed,ios::floatfield); //rnd.seed(now()); int t=1; //cin>>t; rep(i,1,t){ //cout<<"Case #"<<i<<": "; solve(); } } namespace { const int MAX=1'000'005; int n,a[MAX],dp[MAX]; vi pref,stos; void solve() { cin>>n; rep(i,1,n) cin>>a[i]; pref.pb(1); rep(i,2,n) if(a[pref.back()]<a[i]) pref.pb(i); rev(i,1,n){ while(sz(stos)>0 && a[i]>=a[stos.back()]) stos.pop_back(); stos.pb(i); dp[i]=sz(stos); } int curr=0,ans=0; rev(i,1,n){ amax(curr,a[i]); if(pref.back()==i) pref.pop_back(); amax(ans,dp[i]); int l=0,r=sz(pref)-1; while(l<=r){ int mid=(l+r)/2; if(curr<a[pref[mid]]){ amax(ans,dp[i]+sz(pref)-mid); r=mid-1; } else{ l=mid+1; } } } cout<<ans<<endl; } } |
English