Submission #1116929

#	Time	Username	Problem	Language	Result	Execution time	Memory
1116929		vjudge1	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	485 ms	39384 KiB

commuter_pass

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define sort undefined_function // To use stable_sort instead sort 
#define bpc __builtin_popcount
#define ull unsigned long long
#define ld double
#define ll long long
#define mp make_pair
#define F first
#define S second
 
#pragma GCC optimize("O3")
 
#ifdef LOCAL 
	#include "debug.h"
#else 
	#define dbg(...) 0
#endif
 
using namespace __gnu_pbds;
using namespace std;
 
typedef tree<long long, null_type, less_equal<long long>,
    rb_tree_tag, tree_order_statistics_node_update> Tree;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
const ll INF = 9223372036854775807LL;
const ll inf = 2147483647;
const ll MOD = 1e9 + 7; //[998244353, 1e9 + 7, 1e9 + 13]
const ld PI = acos(-1);
const ll NROOT = 500;
 
ll binpow(ll a, ll b, ll _MOD = -1) {
	if (_MOD == -1)
		_MOD = MOD;
	ll res = 1;
	for (; b; b /= 2, a *= a, a %= _MOD)
		if (b & 1) res *= a, res %= _MOD;
	return res;
}
 
void set_IO(string s) {
#ifndef LOCAL
	string in  = s +  ".in";
	string out = s + ".out";
	freopen(in.c_str(),  "r",  stdin);
	freopen(out.c_str(), "w", stdout);
#endif
}
 
bool dataOverflow(ll a, ll b) {return (log10(a) + log10(b) >= 18);}
ll gcd(ll a, ll b) {return b ? gcd(b, a % b) : a;}
ll lcm(ll a, ll b) {return a * b / gcd(a, b);}
ll ceil(ll a, ll b) {return (a + b - 1) / b;}
ll invmod(ll a) {return binpow(a, MOD - 2);}
 
#define int long long
 
int n, m, s, t, u, v;
vector<vector<ll>> dis;
vector<vector<pair<int, ll>>> g;
 
/*
 0 -> s
 1 -> t
 2 -> u
 3 -> v
 */
 
void Dijkstra(int start, int state) {
	using T = pair<ll, int>;
	priority_queue<T, vector<T>, greater<T>> q;
	q.push({0, start});
 
	while (!q.empty()) {
		auto [d, x] = q.top();
		q.pop();
 
		if (dis[state][x] <= d)
			continue;
		dis[state][x] = d;
 
		for (auto &y : g[x]) 
			q.push({d + y.S, y.F});
	}
}
 
int32_t main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
 
	cin >> n >> m >> s >> t >> u >> v;
 
	g.resize(n + 1);
	dis.resize(4, vector<ll> (n + 1, INF));
	for (int i = 1; i <= m; i ++) {
		int a, b; ll c;
		cin >> a >> b >> c;
 
		g[a].push_back({b, c});
		g[b].push_back({a, c});
	}
 
	Dijkstra(s, 0);
	Dijkstra(t, 1);
	Dijkstra(u, 2);
	Dijkstra(v, 3);
 
	queue<pair<int, ll>> q;
	vector<bool> vis(n + 1);
	vector<int> in1(n + 1), in2(n + 1);
	vector<vector<pair<int, ll>>> g1(n + 1), g2(n + 1);
	q.push({t, dis[0][t]});
 
	while (!q.empty()) {
		auto [x, d] = q.front();
		q.pop();
 
		if (vis[x])
			continue;
		vis[x] = 1;
 
		for (auto &y : g[x]) {
			if (dis[0][y.F] + y.S == dis[0][x]) {
				q.push({y.F, dis[0][y.F]});
				g1[y.F].push_back({x, y.S});
				g2[x].push_back({y.F, y.S});
				in1[x] ++;
				in2[y.F] ++;
			}	
		}
	}
 
	vector<vector<ll>> dp1(2, vector<ll> (n + 1, 1e18)); // Minimum distance to U 
	vector<vector<ll>> dp2(2, vector<ll> (n + 1, 1e18)); // Minimum distance to V
 
	for (int i = 1; i <= n; i ++) {
		dp1[0][i] = dp1[1][i] = dis[2][i];
		dp2[0][i] = dp2[1][i] = dis[3][i];
	}
 
	q.push({s, 0});
	q.push({t, 0});
	while (!q.empty()) {
		int x = q.front().F;
		q.pop();
 
		for (auto &y : g1[x]) {
			dp1[0][y.F] = min(dis[2][y.F], dp1[0][x]);
			dp2[1][y.F] = min(dis[3][y.F], dp2[1][x]);
			in1[y.F] --;
			if (in1[y.F] == 0) 
				q.push({y.F, 0});
		}
	}
	q.push({s, 0});
	q.push({t, 0});
	while (!q.empty()) {
		int x = q.front().F;
		q.pop();
 
		for (auto &y : g2[x]) {
			dp1[1][y.F] = min(dis[2][y.F], dp1[1][x]);
			dp2[0][y.F] = min(dis[3][y.F], dp2[0][x]);
			in2[y.F] --;
			if (in2[y.F] == 0) 
				q.push({y.F, 0});
		}
	}
 
	for (int i = 1; i <= n; i ++) {
		dp1[0][i] = min(dp1[0][i], dp1[1][i]);
		dp2[0][i] = min(dp2[0][i], dp2[1][i]);
	}
 
	ll ans = dis[2][v];
	for (int i = 1; i <= n; i ++) 
		ans = min(dp1[0][i] + dp2[0][i], ans);
 
	cout << ans << "\n";
 
	return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void set_IO(std::string)':
commuter_pass.cpp:47:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |  freopen(in.c_str(),  "r",  stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:48:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |  freopen(out.c_str(), "w", stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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