Submission #965798

#	Time	Username	Problem	Language	Result	Execution time	Memory
965798		Gromp15	Swapping Cities (APIO20_swap)	C++17	37 / 100	2104 ms	18820 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; }

const int INF = 1e9;
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) -> bool {
		vector<bool> vis(n+1);
		auto dfs = [&](auto&& s, int v) -> void {
			vis[v] = 1;
			for (auto [u, w, idx] : adj[v]) if (w <= mid && !vis[u]) s(s, u);
		};
		dfs(dfs, X);
		if (!vis[Y]) return 0;
		bool ok = 1;
		for (int i = 1; i <= n; i++) if (vis[i]) {
			int deg = 0;
			for (auto x : adj[i]) deg += x[1] <= mid && vis[x[0]];
			if (deg > 2) { 
				return 1;
			}
			if (deg == 1) ok = 0;
		}
		return ok;
	};
	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: 17 / 17
• Subtask 4: 20 / 20
• Subtask 5: 0 / 23
• Subtask 6: 0 / 27