Submission #1276127

#	Time	Username	Problem	Language	Result	Execution time	Memory
1276127		vibeduck	Fire (BOI24_fire)	C++20	0 / 100	1 ms	580 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;
int s[mxn], e[mxn], nxt[mxn], v[mxn], prv[mxn];
int ans = 1e18;
int cnode = -1;

void dfs(int i) {
    v[i] = 1;
    if (nxt[i] != 0) {
        if (v[nxt[i]] == 1) {
            prv[nxt[i]] = i;
            cnode = i; 
            return;
        }
        if (v[nxt[i]] == 2) return;
        assert(v[nxt[i]] != 2);
        //cout << nxt[i] << " " << i << '\n';
        prv[nxt[i]] = i;
        dfs(nxt[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) {
            if (node == 0) return;
            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;
            // int si = s[i], ei = e[i] + (s[i] > e[i]) * t, sj = s[j], ej = e[j] + (s[j] > e[j]) * t;
            // //cout << si << " " << ei << " " << sj << " " << ej << '\n';
            // if (si <= sj && sj <= ei) mx = max(mx, {ej, j}); 

            bool ok = false;
            if (s[i] > e[i]) {
                if (s[j] > e[j]) {
                    // j bad, i bad
                    if (s[j] >= s[i] || s[j] <= e[i] + 1) ok = true;
                } else {
                    // j good, i bad
                    if (s[j] >= s[i] || s[j] <= e[i] + 1) ok = true;
                }
            } else {
                // ts normal
                if (s[j] > e[j]) {
                    // j bad
                    if (s[j] >= s[i] && s[j] <= e[i] + 1) ok = true;
                } else {
                    // j good
                    if (s[j] >= s[i] && s[j] <= e[i] + 1) ok = true;
                }

                if (e[i] == t - 1 && s[j] == 0) ok = true;
            }

            if (ok) mx = max(mx, {e[j] + (s[j] > e[j]) * t, j});
        }
        nxt[i] = mx.se;
        //cout << nxt[i] << " ";
    }
    //cout << '\n';

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

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

    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:129:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  129 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:130:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  130 |     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