Submission #895575

#	Time	Username	Problem	Language	Result	Execution time	Memory
895575		vjudge1	Split the sequence (APIO14_sequence)	C++17	0 / 100	11 ms	7516 KiB

sequence

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
  
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
 
// #pragma GCC optimize("Ofast,unroll-loops,fast-math")
// #pragma GCC target("popcnt")


typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll,ll> pll;
 
#define sz size()
#define ff first
#define ss second
#define all(a) a.begin(),a.end()
#define pb push_back

const int mod = ll(1e9)+7; //(b + (a%b)) % b (to mod -1%(10^9+7) correctly in c++ its -1 but its suppose to be 10^9+6
const ll MOD = 998244353;  // (a%mod)*(binpow(b,mod-2,mod) = (a/b)%mod
const int N = ll(1e6)+100;
const long long inf = 2e18;
const long double eps = 1e-15L;
 
ll lcm(ll a, ll b) { return (a / __gcd(a,b))*b; }

ll binpow(ll a, ll b, ll m) { ll res=1; a %= m; while(b>0){ if(b&1)res=(res * a) % m; a=(a * a) % m; b/=2; } return res%m;}


void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }

ll n, a[N], c[N], dp[N], pref[N], sum[N];

struct line {
	ll m, b;
};

vector<line> vec;
vector<ld> posx;

ld interx(line a, line b) {
	return (ld)1.0 * (b.b - a.b) / (ld)(a.m - b.m);
}

ll val(line a, ll x) {
	return x * a.m + a.b;
}

bool bad(line a, line b, line c){
    return (b.b - a.b) * (a.m - c.m) >= (c.b - a.b) * (a.m - b.m);
}

void add(line a) {
	while(vec.size() >= 2 && bad(vec[vec.sz - 2], vec.back(), a)) vec.pop_back();
	vec.pb(a);
}

ll get(ll x) {
	if(vec.size() == 1) return val(vec.back(), x);
//	cout<<x<<endl;
//	for(auto v : vec) cout<<val(v, x)<<" ";
//	cout<<endl;
	int l = 0, r = vec.sz - 2;
	while(l <= r) {
		int mid = (l + r) / 2;
		if(val(vec[mid], x) >= val(vec[mid + 1], x)) l = mid + 1;
		else r = mid - 1;
	}
	return val(vec[l], x);
}

void Baizho() {	
	cin>>n;
	for(ll i = 1; i <= n; i ++) {
		cin>>a[i];
		sum[i] = sum[i - 1] + a[i];
		pref[i] = pref[i - 1] + a[i] * i;
	}
	ll ans = pref[n];
	add({n, sum[n]});
	for(ll i = n - 1; i >= 1; i --) {	
		ans = max(ans, -a[i] * i + sum[i] - get(-a[i]) + pref[n]);
		add({i, sum[i]});	
	}
	vec.clear();
	add({-1, 0});
	for(ll i = 2; i <= n; i ++) {
		ans = max(ans, sum[i - 1] - a[i] * i - get(a[i ]) + pref[n]);
		add({-i, sum[i - 1]});
	}
	for(auto x : posx) cout<<x<<" ";
	cout<<ans;
}
 
signed main() {		
 
    ios_base::sync_with_stdio(false);   
    cin.tie(0);cout.tie(0); 
//   	precalc();
   	
    int ttt = 1;
//    cin>>ttt;

    for(int i=1; i<=ttt; i++) { Baizho(); }
}

Compilation message (stderr)

sequence.cpp: In function 'void Freopen(std::string)':
sequence.cpp:35:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 | void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }
      |                           ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:35:76: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 | void Freopen(string Key){ freopen((Key+".in").c_str(), "r", stdin); freopen((Key+".out").c_str(), "w", stdout); }
      |                                                                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 11
• Subtask 3: 0 / 11
• Subtask 4: 0 / 17
• Subtask 5: 0 / 21
• Subtask 6: 0 / 29