Submission #1261841

#	Time	Username	Problem	Language	Result	Execution time	Memory
1261841		CrabCNH	Fire (BOI24_fire)	C++20	100 / 100	231 ms	72560 KiB

Main

#include <bits/stdc++.h>

#define task     "BriantheCrab"

#define int    long long
#define pii    pair <int, int>
#define fi     first
#define se     second
#define szf    sizeof
#define sz(s)  (int)((s).size())
#define all(v) (v).begin(), (v).end()

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

using namespace std;

template <class T> void minimize (T &t, T f) {if (t > f) t = f;}
template <class T> void maximize (T &t, T f) {if (t < f) t = f;}

const int maxN = 4e5 + 5;
const int inf = 1e18 + 7;
const int mod = 1e9 + 7;
const int LOG = 21;

// khong tu code thi khong kha len duoc dau
// biet sol roi thi tu lam not di

int n, m;
pii a[maxN];
int nxt[maxN][LOG];

void solve () {
    cin >> n >> m;
    vector <int> zip;
    for (int i = 1; i <= n; i ++) {
        int l, r;
        cin >> l >> r;
        a[i] = {l, r};
        zip.push_back (l);
        zip.push_back (r);    
    }
    sort (all (zip));
    zip.erase (unique (all (zip)), zip.end ());
    for (int i = 1; i <= n; i ++) {
        a[i].fi = lower_bound (all (zip), a[i].fi) - zip.begin () + 1;
        a[i].se = lower_bound (all (zip), a[i].se) - zip.begin () + 1;
    }
    m = sz (zip) + 1;
    for (int i = 1; i <= n; i ++) {
        if (a[i].fi < a[i].se) {
            maximize (nxt[a[i].fi][0], a[i].se);
        }
    }
    for (int i = 1; i <= m; i ++) {
        maximize (nxt[i][0], nxt[i - 1][0]);
    }
    for (int j = 1; j < LOG; j ++) {
        for (int i = 1; i <= m; i ++) {
            maximize (nxt[i][j], nxt[nxt[i][j - 1]][j - 1]);
        }
        for (int i = 1; i <= m; i ++) {
            maximize (nxt[i][j], nxt[i - 1][j]);
        }
    }
    //cout << nxt[4][0] << '\n';
    int res = inf;
    for (int i = 1; i <= n; i ++) {
        if (a[i].fi < a[i].se) {
            continue;
        }
        int cost = 1;
        int st = a[i].se, en = a[i].fi;
        for (int j = LOG - 1; j >= 0; j --) {
            if (nxt[st][j] > 0 && nxt[st][j] < en) {
                cost += (1 << j);
                //cout << nxt[st][j] << ' ' << st << ' ' << j << '\n';
                st = nxt[st][j];
            }
        }
        if (nxt[st][0] >= en) {
            minimize (res, cost + 1);
        }
    }
    cout << (res > n ? -1 : res);
    return;
}

signed main () {
    cin.tie (nullptr) -> sync_with_stdio (false);
    if (fopen (task".inp", "r")) {
        freopen (task".inp", "r", stdin);
        freopen (task".out", "w", stdout);
    }
    int t = 1;
    //cin >> t;
    while (t --) {
        solve ();
    } 
    return 0;
}
// thfvz

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:93:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |         freopen (task".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:94:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   94 |         freopen (task".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 17 / 17
• Subtask 3: 9 / 9
• Subtask 4: 13 / 13
• Subtask 5: 21 / 21
• Subtask 6: 26 / 26