Submission #965728

#	Time	Username	Problem	Language	Result	Execution time	Memory
965728		Gromp15	Swapping Cities (APIO20_swap)	C++17	0 / 100	2100 ms	11436 KiB

swap

#include "swap.h"
#include <bits/stdc++.h>
using namespace std;
#define sz(x) int(x.size())
#define all(x) x.begin(), x.end()
#define db double
#define ll long long
#define ar array
template<typename T> bool ckmin(T& a, const T& b) { return a > b ? a = b, 1 : 0; }
template<typename T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }

vector<vector<ar<int, 3>>> adj;
int n, m;

void init(int N, int M,
          std::vector<int> U, std::vector<int> V, std::vector<int> W) {
	n = N, m = M;
	adj.resize(N + 1);
	for (int i = 0; i < M; i++) {
		adj[U[i]].push_back({V[i], W[i], i});
		adj[V[i]].push_back({U[i], W[i], i});
	}
}

int getMinimumFuelCapacity(int X, int Y) {
	auto good = [&](int mid) {
		vector<int> dist(n+1, 1e9), p(n+1), who(n+1);
		queue<int> q;
		q.push(X), dist[X] = 0;
		while (q.size()) {
			int v = q.front(); q.pop();
			for (auto [u, w, idx] : adj[v]) if (w <= mid && ckmin(dist[u], dist[v] + 1)) {
				q.push(u);
				p[u] = v, who[u] = idx;
			}
		}
		if (dist[Y] == int(1e9)) return 0;
		vector<bool> bad(m);
		for (int s = Y, from = -1; s != X; from = s, s = p[s]) {
			bad[who[s]] = 1;
			if (s != Y) {
				for (auto x : adj[s]) {
					if (x[1] <= mid && x[0] != p[s] && x[0] != from) {
						return 1;
					}
				}
			}
		}
		vector<bool> vis2(n+1);
		vis2[X] = 1;
		q.push(X);
		while (q.size()) {
			int v = q.front(); q.pop();
			if (v == Y) return 1;
			for (auto [u, w, idx] : adj[v]) if (w <= mid && !bad[idx] && !vis2[u]) {
				vis2[u] = 1, q.push(u);
			}
		}
		return 0;
	};
	int l = 1, r = 1e9, ans = 1e9;
	if (!good(r)) return -1;
	while (l <= r) {
		int mid = (l+r)/2;
		if (good(mid)) ans = mid, r = mid-1;
		else l = mid+1;
	}
	return ans;
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 7
• Subtask 3: 0 / 17
• Subtask 4: 0 / 20
• Subtask 5: 0 / 23
• Subtask 6: 0 / 27