Submission #207830

#	Time	Username	Problem	Language	Result	Execution time	Memory
207830		opukittpceno_hhr	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	844 ms	28264 KiB

commuter_pass

#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <fstream>
#include <cassert>
#include <cstring>
#include <unordered_set>
#include <unordered_map>
#include <numeric>
#include <ctime>
#include <bitset>
#include <complex>
#include <random>

using namespace std;

#define int long long

const int N = 1e5 + 7;
const int INF = 1e18 + 239;

int n;
vector<pair<int, int>> g[N];

vector<int> dj(int st) {
	vector<int> d(n, INF);
	set<pair<int, int>> s;
	d[st] = 0;
	s.insert({d[st], st});
	while (!s.empty()) {
		int v = s.begin()->second;
		s.erase(s.begin());
		for (auto [u, w] : g[v]) {
			if (d[u] > d[v] + w) {
				s.erase({d[u], u});
				d[u] = d[v] + w;
				s.insert({d[u], u});
			}
		}
	}
	return d;
}

vector<pair<int, int>> ng[N];

vector<int> ds;
vector<int> dt;

int s, t;

void init() {
	ds = dj(s);
	dt = dj(t);
	for (int i = 0; i < n; i++) {
		for (auto [u, w] : g[i]) {
			if (ds[i] + w + dt[u] == ds[t]) {
				ng[i].push_back({u, w});
			} else {
				// ng[i].push_back({u, w});
			}
		}
	}
}

int dp[N];
vector<int> du;
vector<int> dv;

int calc(int x) {
	if (dp[x] == -1) {
		dp[x] = dv[x];
		for (auto [t, w] : ng[x]) {
			dp[x] = min(dp[x], calc(t));
		}
	}
	return dp[x];
}

int solve(int u, int v) {
	du = dj(u);
	dv = dj(v);
	fill(dp, dp + n, -1);
	int ans = du[v];
	for (int i = 0; i < n; i++) {
		ans = min(ans, du[i] + calc(i));
	}
	return ans;
}

signed main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);

	int m;
	cin >> n >> m;
	int u, v;
	cin >> s >> t >> u >> v;
	s--;
	t--;
	u--;
	v--;
	while (m--) {
		int a, b, c;
		cin >> a >> b >> c;
		a--;
		b--;
		g[a].push_back({b, c});
		g[b].push_back({a, c});
	}
	init();
	int ans = min(solve(u, v), solve(v, u));
	cout << ans << endl;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'long long int calc(long long int)':
commuter_pass.cpp:79:18: warning: unused variable 'w' [-Wunused-variable]
   for (auto [t, w] : ng[x]) {
                  ^

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 45 / 45