Submission #1268768

#	Time	Username	Problem	Language	Result	Execution time	Memory
1268768		quangminh412	Global Warming (CEOI18_glo)	C++17	100 / 100	342 ms	34808 KiB

glo

/*
  Ben Watson

  Quang Minh MasterDDDDD
*/

#include <bits/stdc++.h>
using namespace std;

#define ll long long

const string name = "stellar";

void solve();
signed main()
{
    if (fopen((name + ".inp").c_str(), "r"))
    {
        freopen((name + ".inp").c_str(), "r", stdin);
        freopen((name + ".out").c_str(), "w", stdout);
    }
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    solve();

    return 0;
}

// main program
const int maxn = 2e5 + 1;

struct FenwickTree
{
    vector<int> bits;
    int n;

    FenwickTree(int n) : n(n) { bits.resize(n + 1, 0); }
    void reset() { for (int i = 0; i <= n; i++) bits[i] = 0; }

    void update(int pos, int val)
    {
        for (; pos <= n; pos += (pos & (-pos)))
            bits[pos] = max(bits[pos], val);
    }

    int query(int pos)
    {
        int res = 0;
        for (; pos > 0; pos -= (pos & (-pos)))
            res = max(res, bits[pos]);
        return res;
    }
};

unordered_map<int, int> mp;
int a[maxn], L[maxn], R[maxn], cmp[maxn];
vector<int> proc;
int n, x, m;

void solve()
{
    cin >> n >> x;
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i];
        proc.push_back(a[i]);
        proc.push_back(a[i] - x);
        proc.push_back(a[i] + x);
    }

    m = 0;
    sort(proc.begin(), proc.end());
    for (int x : proc)
        if (mp[x] == 0)
            mp[x] = ++m;
    for (int i = 1; i <= n; i++)
        cmp[i] = mp[a[i]];

    FenwickTree bit_L(m);
    for (int i = 1; i <= n; i++)
    {
        L[i] = 1 + bit_L.query(cmp[i] - 1);
        bit_L.update(cmp[i], L[i]);
    }
    FenwickTree bit_R(m);
    for (int i = n; i > 0; i--)
    {
        R[i] = 1;
        if (cmp[i] != m)
            R[i] = 1 + bit_R.query(m + 1 - (cmp[i] + 1));
        bit_R.update(m + 1 - cmp[i], R[i]);
    }

    int res = 0;
    bit_L.reset();
    for (int i = 1; i <= n; i++)
    {
        int tmp = 1 + bit_L.query(cmp[i] - 1);
        res = max(res, R[i] + bit_L.query(mp[a[i] + x] - 1));
        bit_L.update(cmp[i], tmp);
    }
    bit_R.reset();
    for (int i = n; i > 0; i--)
    {
        int tmp = 1;
        if (cmp[i] != m)
            tmp = 1 + bit_R.query(m + 1 - (cmp[i] + 1));
        int pos = upper_bound(proc.begin(), proc.end(), a[i] - x) - proc.begin();
        if (pos != (int)proc.size())
            res = max(res, L[i] + bit_R.query(m + 1 - mp[proc[pos]]));
        bit_R.update(m + 1 - cmp[i], tmp);
    }

    cout << res << '\n';
}

Compilation message (stderr)

glo.cpp: In function 'int main()':
glo.cpp:19:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   19 |         freopen((name + ".inp").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
glo.cpp:20:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 |         freopen((name + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 13 / 13
• Subtask 4: 10 / 10
• Subtask 5: 20 / 20
• Subtask 6: 17 / 17
• Subtask 7: 25 / 25