Submission #58968

#	Time	Username	Problem	Language	Result	Execution time	Memory
58968		Benq	Hacker (BOI15_hac)	C++14	100 / 100	119 ms	25664 KiB

hac

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;
 
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;

#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)

#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()

const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 500001;

int v[MX], opt[MX], N;

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> N;
    FOR(i,1,N+1) cin >> v[i];
    int K = (N+1)/2;
    FOR(i,1,K+1) opt[1] += v[i];
    FOR(i,2,N+1) {
        opt[i] = opt[i-1];
        opt[i] -= v[i-1];
        if (i+K-1 <= N) opt[i] += v[i+K-1];
        else opt[i] += v[i+K-1-N];
    }
    deque<pi> d;
    int ans = 0;
    FOR(i,1,2*N+1) {
        int I = i%N; if (I == 0) I = N;
        // i to i-K+1 
        while (sz(d) && d.back().f >= opt[I]) d.pop_back();
        d.pb({opt[I],i});
        while (d.front().s <= i-K) d.pop_front();
        if (i >= K) ans = max(ans,d.front().f);
    }
    cout << ans;
}

/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( ) 
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 40 / 40