Submission #676168

#	Time	Username	Problem	Language	Result	Execution time	Memory
676168		stevancv	Aesthetic (NOI20_aesthetic)	C++14	100 / 100	495 ms	41872 KiB

Aesthetic

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 3e5 + 2;
const ll linf = 1e18;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n, m;
    cin >> n >> m;
    vector<int> u(m), v(m), w(m), suff(m);
    vector<vector<pair<int, int>>> g(n);
    for (int i = 0; i < m; i++) {
        cin >> u[i] >> v[i] >> w[i];
        u[i] -= 1; v[i] -= 1;
        g[u[i]].push_back({v[i], i});
        g[v[i]].push_back({u[i], i});
    }
    for (int i = m - 2; i >= 0; i--) suff[i] = max(suff[i + 1], w[i + 1]);
    function<vector<ll>(int)> Dijk = [&] (int s) {
        vector<ll> dist(n, linf);
        priority_queue<pair<ll, int>> q;
        q.push({0, s});
        while (!q.empty()) {
            auto s = q.top(); q.pop();
            s.first *= -1;
            if (dist[s.second] <= s.first) continue;
            dist[s.second] = s.first;
            for (auto u : g[s.second]) {
                if (dist[u.first] == linf) q.push({-s.first - w[u.second], u.first});
            }
        }
        return dist;
    };
    vector<ll> a = Dijk(0);
    vector<ll> b = Dijk(n - 1);
    ll l = b[0], r = b[0] + suff[0];
    auto Greater = [&] (ll x) {
        int is = 0;
        vector<int> dep(n, -1), mn(n);
        int tsz = 0;
        function<void(int, int)> Dfs = [&] (int s, int e) {
            dep[s] = mn[s] = tsz++;
            for (auto u : g[s]) {
                if (u.first == e) continue;
                ll y = min(a[s] + b[u.first], a[u.first] + b[s]) + w[u.second];
                if (y > x) continue;
                if (dep[u.first] == -1) {
                    Dfs(u.first, s);
                    smin(mn[s], mn[u.first]);
                    if (mn[u.first] > dep[s] && y + suff[u.second] > x && dep[n - 1] >= mn[u.first]) {
                        is = 1;
                        break;
                    }
                }
                else smin(mn[s], dep[u.first]);
            }
        };
        Dfs(0, -1);
        return is;
    };
    while (l < r) {
        ll mid = l + r >> 1;
        if (Greater(mid)) l = mid + 1;
        else r = mid;
    }
    cout << l << en;
    return 0;
}

Compilation message (stderr)

Aesthetic.cpp: In function 'int main()':
Aesthetic.cpp:69:20: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   69 |         ll mid = l + r >> 1;
      |                  ~~^~~

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 7 / 7
• Subtask 4: 15 / 15
• Subtask 5: 16 / 16
• Subtask 6: 22 / 22
• Subtask 7: 27 / 27