Submission #1124382

#	Time	Username	Problem	Language	Result	Execution time	Memory
1124382		seoul_korea	Candies (JOI18_candies)	C++17	100 / 100	80 ms	10876 KiB

candies

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define REP(i, n) for(int i = 1; i <= n; i++)
#define FOR(i, a, b) for(auto i = a; i <= b; i++)
#define FORD(i, a, b) for(auto i = a; i >= b; i--)
template<class T> bool maximize(T& a, T b) { if(a < b) return a = b, 1; return 0; }
template<class T> bool minimize(T& a, T b) { if(a > b) return a = b, 1; return 0; }
mt19937 rng(time(0));

const int N = (int)2e5 + 7;
int a[N];
int n;

namespace Subtask1
{
    const int maxN = 2007;
    int f[maxN][maxN];

    bool Check()
    {
        return n <= 2000;
    }

    void Calc(int k)
    {
        REP(i, n)
        {
            if(f[i - 1][k]) f[i][k] = f[i - 1][k];
            if(i - 2 > 0 and f[i - 2][k - 1]) maximize(f[i][k], f[i - 2][k - 1] + a[i]);
        }
    }

    void Solve()
    {
        REP(i, n)
            f[i][1] = max(a[i], f[i - 1][1]);
        REP(i, (n + 1) / 2)
        {
            if(i > 1) Calc(i);
            int ans = 0;
            REP(j, n)
                maximize(ans, f[j][i]);
            cout << ans << '\n';
        }
    }
}

namespace Subtask2
{
    bool del[N];
    int ans[(N + 1) / 2];
    int nxt[N], prv[N];

    void Solve()
    {
        priority_queue<pair<int, int>> pq;
        REP(i, n)
        {
            pq.push({a[i], i});
            nxt[i] = i + 1;
            prv[i] = i - 1;
        }
        nxt[0] = 1;
        prv[n + 1] = n;
        int cnt = 0, s = 0;
        a[0] = a[n + 1] = -1e18;
        while(pq.size() and cnt < (n + 1) / 2)
        {
            pair<int, int> x = pq.top();
            pq.pop();
            int id = x.second;
            int w = x.first;
            if(del[id])
                continue;
            s += w;
            ++cnt;
            maximize(ans[cnt], s);
            del[nxt[id]] = 1;
            del[prv[id]] = 1;
            a[id] = a[nxt[id]] + a[prv[id]] - w;
            nxt[id] = nxt[nxt[id]];
            prv[id] = prv[prv[id]];
            prv[nxt[id]] = nxt[prv[id]] = id;
            pq.push({a[id], id});
        }
        REP(i, cnt)
            cout << ans[i] << '\n';
    }
}

signed main(void)
{
    cin.tie(nullptr)->sync_with_stdio(false);
    #define TASK ""
    if(fopen(TASK".INP", "r"))
    {
        freopen(TASK".INP", "r", stdin);
        freopen(TASK".OUT", "w", stdout);
    }

    cin >> n;
    REP(i, n)
        cin >> a[i];
//    if(Subtask1::Check()) return Subtask1::Solve(), 0;
    return Subtask2::Solve(), 0;
    return 0;
}

Compilation message (stderr)

candies.cpp: In function 'int main()':
candies.cpp:100:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  100 |         freopen(TASK".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
candies.cpp:101:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |         freopen(TASK".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 92 / 92