Submission #1182903

#	Time	Username	Problem	Language	Result	Execution time	Memory
1182903		nagorn_ph	Airplane (NOI23_airplane)	C++20	100 / 100	885 ms	25692 KiB

Main

#include <bits/stdc++.h>
#define int long long
#define double long double
#define pii pair <int,int>
#define tiii tuple <int, int, int>
#define f first
#define s second
#define all(x) x.begin(), x.end()
#define ub(a, b) upper_bound(a.begin(), a.end(), b) - a.begin()
#define lb(a, b) lower_bound(a.begin(), a.end(), b) - a.begin()
#define ve vector
#define graph(a, n) vector <int> a[n];
#define wgraph(a, n) vector <pii> a[n];
#define emb emplace_back
#define em emplace
#define ins insert
#define er erase
#define iShowSpeed cin.tie(NULL)->sync_with_stdio(false)

using namespace std;

template <typename T>
using greater_priority_queue = priority_queue<T, vector<T>, greater<T>>;

const int mod = 1e9 + 7;
const int inf = 1e18;
const int N = 2e5 + 5;

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

int n, m, a[N];
vector <int> adj[N];

vector <int> dijkstra(int st){
    greater_priority_queue <pii> q; q.emplace(0, st);
    vector <int> dis(n + 1, inf); dis[st] = 0;
    while (!q.empty()) {
        auto [w, u] = q.top(); q.pop();
        if (w > dis[u]) continue;
        for (auto v : adj[u]) {
            int ww = max(w + 1, a[v]);
            if (ww >= dis[v]) continue;
            dis[v] = ww;
            q.emplace(dis[v], v);
        }
    }
    return dis;
}

int32_t main(){
    iShowSpeed;
    cin >> n >> m;
    for (int i = 1; i <= n; i++) cin >> a[i];
    for (int i = 0; i < m; i++) {
        int u, v; cin >> u >> v;
        adj[u].emb(v);
        adj[v].emb(u);
    }
    vector <int> dis1 = dijkstra(1);
    vector <int> dis2 = dijkstra(n);
    int l = 0, r = inf, ans = inf;
    while (l <= r) {
        int mid = (l + r) / 2;
        vector <bool> ok(n + 1);
        for (int i = 1; i <= n; i++) {
            if (dis1[i] + dis2[i] <= mid) ok[i] = true;
        }
        vector <bool> visited(n + 1);
        queue <int> q; if (ok[1]) q.emplace(1), visited[1] = true;
        while (!q.empty()) {
            auto u = q.front(); q.pop();
            for (auto v : adj[u]) {
                if (!visited[v] && ok[v]) {
                    visited[v] = true;
                    q.emplace(v);
                }
            }
        }
        if (visited[n]) {
            r = mid - 1;
            ans = min(ans, mid);
        }
        else l = mid + 1;
    }
    cout << ans;
}

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