Submission #1276120

#	Time	Username	Problem	Language	Result	Execution time	Memory
1276120		vibeduck	Fire (BOI24_fire)	C++20	0 / 100	2 ms	724 KiB

Main

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

#define pb push_back
#define pf push_front
#define mp make_pair
#define fi first
#define se second
#define int long long
#define all(x) (x).begin(), (x).end()

typedef long double ld;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<vector<bool>> vvb;
typedef vector<vector<ll>> vvll;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef vector<char> vc;
typedef vector<vector<char>> vvc;
typedef map<int, int> mii;
typedef unordered_map<int, int> umii;

const int mod = 1e9 + 7;
const int inf = INTMAX_MAX;
const bool tc = false;

int n, t;
const int mxn = 2e5 + 1;
const int lt = 21;
int s[mxn], e[mxn], p[mxn], v[mxn], prv[mxn];
int ans = 1e18;
int cnode = -1;

void dfs(int i) {
    v[i] = 1;
    if (p[i] != 0) {
        if (v[p[i]] == 1) {
            cnode = i;
            return;
        }
        dfs(p[i]);
    }
    v[i] = 2;
}

void cycle(int i) {
    cnode = -1;
    dfs(i);
    if (cnode != -1) {
        int node = prv[cnode];
        int l = 1;
        while (node != cnode) {
            assert(node != 0);
            assert(cnode != 0);
            l++;
            node = prv[node];
        }
        ans = min(ans, l);
    }
}

// size of smallest cycle

inline void solve() {
    int n, t; cin >> n >> t; set<int> x;
    for (int i = 1; i <= n; i++) cin >> s[i] >> e[i];

    // find parent
    for (int i = 1; i <= n; i++) {
        pii mx = {-1e18, 0};
        for (int j = 1; j <= n; j++) {
            if (i == j) continue;
            if (e[i] < s[j]) continue;
            mx = max(mx, {e[j] + (s[j] > e[j]) * t, j});
        }
        p[i] = mx.se;
        prv[p[i]] = i;
    }

    //for (int i = 1; i <= n; i++) cout << p[i] << " ";
    //cout << '\n';

    //cycle(1);

    for (int i = 1; i <= n; i++) {
        if (!v[i]) cycle(i);
    }

    cout << (ans != 1e18 ? ans : -1) << '\n';
}

void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

signed main() {
    ios::sync_with_stdio(false);
    cout.tie(0);
    cin.tie(0);
    //setIO();

    int t = 1;
    if (tc) {
        cin >> t;
    }

    while (t--) {
        solve();
    }
}

Compilation message (stderr)

Main.cpp: In function 'void setIO(std::string)':
Main.cpp:99:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   99 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:100:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  100 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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