Submission #1281407

#	Time	Username	Problem	Language	Result	Execution time	Memory
1281407		red_souls	Fire (BOI24_fire)	C++17	40 / 100	2095 ms	8348 KiB

Main

#include <bits/stdc++.h>
#define ll long long
#define task "FIRE"
using namespace std;

const int N = 5e5 + 16;
const ll INF = 1e9;
int n, m;
ll s[N], e[N];

namespace sub3 {
    ll cnt, result = INF;
    pair <ll, ll> a[N];

    vector < pair <ll, ll> > checkLines;

    bool cmp(pair <ll, ll> a, pair <ll, ll> b) {
        if (a.first == b.first) {
            return a.second > b.second;
        }
        return a.first < b.first;
    }

    ll query(pair <ll, ll> target) {
        ll curP = 1, p = target.first, cnt = 0;
        while (p <= target.second) {
            ll r = -1;
            while (curP <= n && a[curP].first <= p) {
                r = max(a[curP].second, r);
                curP++;
            }
            if (r < p) {
                return -1;
            }
            p = r + 1;
            cnt++;
        }
        return cnt;
    }

    void solve() {
        checkLines.push_back({0, m - 1});
        for (int i = 1; i <= n; i++) {
            if (s[i] > e[i]) {
                checkLines.push_back({e[i], e[i] + m - 1});
                e[i] += m;
            }
            a[i] = {s[i], e[i] - 1};
        }
        sort(a + 1, a + 1 + n, cmp);
        for (auto x : checkLines) {
            ll ans = query(x);
            if (ans == -1) {
                continue;
            }
            result = min(result, ans);
        }
        if (result == INF) {
            result = -1;
        }
        cout << result;
    }
}

int main() {
    ios_base :: sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    if (fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }

    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        cin >> s[i] >> e[i];
    }
    sub3 :: solve();

    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:71:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:72:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 17 / 17
• Subtask 3: 9 / 9
• Subtask 4: 0 / 13
• Subtask 5: 0 / 21
• Subtask 6: 0 / 26