Submission #882727

#	Time	Username	Problem	Language	Result	Execution time	Memory
882727		tsumondai	Airplane (NOI23_airplane)	C++14	100 / 100	414 ms	53964 KiB

Main

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

#define int long long
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define foru(i, l, r) for(int i = l; i <= r; i++)
#define ford(i, r, l) for(int i = r; i >= l; i--)
#define __TIME  (1.0 * clock() / CLOCKS_PER_SEC)

typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;

const int N = 1e6 + 5;

const int oo = 1e18, mod = 1e9 + 7;

int n, m, k, h[N];
string s;
vector<int> adj[N];

int dist[N][2];

void dijkstra(int s, int source) {
    foru(i, 0, n + 1) dist[i][source] = oo;
    priority_queue <pair <long long, int>> pq;
    pq.push(make_pair(dist[s][source] = 0, s));
    while (!pq.empty()) {
        pair<long long, long long> tmp = pq.top(); pq.pop();
        long long du = tmp.first, u = tmp.second;
        du = -du;
        if (du != dist[u][source]) continue;
        for (int v : adj[u]) if (dist[v][source] > max(h[v], dist[u][source] + 1)) {
                dist[v][source] = max(h[v], dist[u][source] + 1);
                pq.push(make_pair(-dist[v][source], v));
            }
    }
}

void process() {
    // 0: from 1
    // 1: from n
    cin >> n >> m;
    foru(i, 1, n) cin >> h[i];
    foru(i, 1, m) {
        int u, v; cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }

    dijkstra(1, 0);
    dijkstra(n, 1);
    int ans = oo;

    foru(u, 1, n) {
        ans = min(ans, max(dist[u][0], dist[u][1]) * 2);
        for (int v : adj[u]) {
            ans = min(ans, max(dist[v][0], dist[u][1]) * 2 + 1);
            ans = min(ans, max(dist[u][0], dist[v][1]) * 2 + 1);
        }
    }
    cout << ans;
    return;
}

signed main() {
    cin.tie(0)->sync_with_stdio(false);
    //freopen(".inp", "r", stdin);
    //freopen(".out", "w", stdout);
    process();
    cerr << "Time elapsed: " << __TIME << " s.\n";
    return 0;
}

/*
Xét các trường hợp đặc biệt
Kiểm tra lại input/output
Cố gắng trâu
Lật ngược bài toán
Keep calm and get VOI
Flow:

*/

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