Submission #1291798

#	Time	Username	Problem	Language	Result	Execution time	Memory
1291798		nqc	Global Warming (CEOI18_glo)	C++20	100 / 100	105 ms	6116 KiB

glo

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

#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pli pair<ll, int>
#define debug(x) cout << #x << " = " << x << '\n'
#define all(a) a.begin(), a.end()
#define SZ(a) (int)(a).size()

const int N = 2e5 + 5;
const int mod = 1e9 + 7;
const ll inf64 = 3e18;
const int inf32 = 2e9 + 5;

int n, X, a[N];

struct FenwickTree {
    int n;
    vector<int> node;
    FenwickTree() {}
    FenwickTree(int n) : n(n), node(n + 3, 0) {}
    void upd(int i, int x) {
        for(; i <= n; i += i & (-i)) 
            node[i] = max(node[i], x);
    }
    int get(int i) {
        int res = 0;
        for(; i; i -= i & (-i)) 
            res = max(res, node[i]);
        return res;
    }
};

void solve() {
    cin >> n >> X;
    vector<int> cprs;
    for(int i = 1; i <= n; i++) {
        cin >> a[i];
        cprs.push_back(a[i]);
        cprs.push_back(a[i] + X);
    }

    sort(all(cprs)); cprs.erase(unique(all(cprs)), cprs.end());

    auto take = [&](int val) -> int {
        return lower_bound(all(cprs), val) - cprs.begin() + 1;
    };  

    int ans = 0;
    FenwickTree fen0(SZ(cprs)), fen1(SZ(cprs));
    for(int i = 1; i <= n; i++) {
        int p = take(a[i]), q = take(a[i] + X);

        int dp0 = fen0.get(p - 1) + 1;
        int dp1 = max(fen1.get(p - 1) + 1, fen0.get(q - 1) + 1);

        ans = max({ans, dp0, dp1});

        fen0.upd(p, dp0); 
        fen1.upd(p, dp1);
    }
    cout << ans << '\n';
}

int main() {
    auto start = chrono::steady_clock::now();

    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if(fopen("input.txt", "r")) {
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    }
    int test = 1; 
    // cin >> test;
    while(test--) solve();
    
    chrono::duration<double> elapsed {chrono::steady_clock::now() - start};
    cerr << "\n>> Runtime: " << elapsed.count() << "s\n";
}

Compilation message (stderr)

glo.cpp: In function 'int main()':
glo.cpp:75:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |         freopen("input.txt", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
glo.cpp:76:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |         freopen("output.txt", "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