Submission #886678

#	Time	Username	Problem	Language	Result	Execution time	Memory
886678		fanwen	Airplane (NOI23_airplane)	C++17	100 / 100	291 ms	24544 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define MASK(x) (1LL << (x))
#define BIT(x, i) (((x) >> (i)) & 1)
#define ALL(x) (x).begin(), (x).end()
#define REP(i, n) for (int i = 0, _n = n; i < _n; ++i)
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORD(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
#define FORE(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define debug(...) "[" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }

template <class A, class B> bool minimize(A &a, B b)  { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b)  { if (a < b) { a = b; return true; } return false; }

const int MAXN = 2e5 + 5;

int N, M, a[MAXN], dpL[MAXN], dpR[MAXN];

vector <int> adj[MAXN];

void dijkstra(int s, int dp[]) {
    fill(dp + 1, dp + N + 1, 1e9);
    dp[s] = a[s];
    priority_queue <pair <int, int>, vector <pair <int, int>>, greater_equal <pair <int, int>>> q;
    q.emplace(dp[s], s);
    while(q.size()) {
        auto [du, u] = q.top(); q.pop();
        if(dp[u] != du) continue;
        for (auto v : adj[u]) if(minimize(dp[v], max(dp[u] + 1, a[v]))) {
            q.emplace(dp[v], v);
        }
    }
}

void you_make_it(void) {
    cin >> N >> M;
    FOR(i, 1, N) cin >> a[i];
    while(M--) {
        int u, v; cin >> u >> v;
        adj[u].emplace_back(v);
        adj[v].emplace_back(u);
    }
    int res = 2e9;
    dijkstra(1, dpL);
    dijkstra(N, dpR);
    FOR(i, 1, N) {
        minimize(res, 2 * max(dpL[i], dpR[i]));
    }
    // FOR(i, 1, N) cout << dpL[i] << " \n"[i == N];
    // FOR(i, 1, N) cout << dpR[i] << " \n"[i == N];
    FOR(u, 1, N) for (auto v : adj[u]) {
        minimize(res, 2 * max(dpL[u], dpR[v]) + 1);
    }
    cout << res;
}

signed main() {

#ifdef LOCAL
    freopen("TASK.inp", "r", stdin);
    freopen("TASK.out", "w", stdout);
#endif
  	file("airplane");
    auto start_time = chrono::steady_clock::now();

    cin.tie(0), cout.tie(0) -> sync_with_stdio(0);

    you_make_it();

    auto end_time = chrono::steady_clock::now();

    cerr << "\nExecution time : " << chrono::duration_cast <chrono::milliseconds> (end_time - start_time).count() << "[ms]" << endl;

    return (0 ^ 0);
}

// Dream it. Wish it. Do it.

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:13:57: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 | #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:66:4: note: in expansion of macro 'file'
   66 |    file("airplane");
      |    ^~~~
Main.cpp:13:90: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 | #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                                                   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:66:4: note: in expansion of macro 'file'
   66 |    file("airplane");
      |    ^~~~

• Subtask 1: 22 / 22
• Subtask 2: 10 / 10
• Subtask 3: 31 / 31
• Subtask 4: 37 / 37