Submission #336546

#	Time	Username	Problem	Language	Result	Execution time	Memory
336546		Galebickosikasa	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	848 ms	30680 KiB

commuter_pass

// #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx")
// #pragma comment(linker, "/stack:200000000"]
 
#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <unordered_set>
#include <unordered_map>
#include <set>
#include <map>
#include <queue>
#include <deque>
#include <bitset>
#include <stack>
#include <random>
#include <fstream>
#include <sstream>
#include <chrono>

#define fi first
#define se second
#define pb push_back
#define ll long long
#define ld long double
#define hm unordered_map 
#define pii pair<int, int>
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define cinv(v) for (auto& x: v) cin >> x
#define fr(i, n) for (int i = 0; i < n; ++i)
#define fl(i, l, n) for (int i = l; i < n; ++i)

#define int ll

template <typename T1, typename T2> inline bool chkmin(T1 &x, const T2 &y) {if (x > y) {x = y; return 1;} return 0;}
template <typename T1, typename T2> inline bool chkmax(T1 &x, const T2 &y) {if (x < y) {x = y; return 1;} return 0;}

using namespace std;

#ifdef LOCAL
	#define dbg(x) cerr << #x << " : " << x << '\n'
	const int maxn = 20;
#else 
	#define dbg(x)
	const int maxn = 1e5 + 20;
#endif

//tg: @galebickosikasa
 
ostream& operator << (ostream& out, const pii& v) {
	out << v.fi << ", " << v.se;
	return out;
}

template<typename T> ostream& operator << (ostream& out, const vector<T>& v) {
    for (auto& x: v) out << x << " ";
    return out;
}

istream& operator >> (istream& in, pii& a) {
	in >> a.fi >> a.se;
	return in;
}

const ll inf = (ll) 1e18;
const ld pi = asin (1) * 2;
const ld eps = 1e-8;
const ll mod = (ll)1e9 + 7;
const ll ns = 97;

mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

vector<pii> g[maxn];
vector<int> G[maxn];
int dp[maxn], used[maxn];

vector<int> Dijkstra (int s, int n) {
	vector<int> d (n, inf);
	d[s] = 0;
	set <pii> a;
	a.insert ({0, s});
	while (!a.empty ()) {
		int v = a.begin ()->se;
		a.erase (a.begin ());
		for (auto& u: g[v]) {
			if (d[u.fi] > d[v] + u.se) {
				a.erase ({d[u.fi], u.fi});
				d[u.fi] = d[v] + u.se;
				a.insert ({d[u.fi], u.fi});
			}
		}
	}
	return d;
}

void calc (int v, vector<int>& d) {
	used[v] = 1;
	dp[v] = d[v];
	for (auto& u: G[v]) {
		if (!used[u]) calc (u, d);
		chkmin (dp[v], dp[u]);
	}
}

signed main () {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	int n, m;
	cin >> n >> m;
	int s, t;
	cin >> s >> t;
	--s, --t;
	int u, v;
	cin >> u >> v;
	--u, --v;
	for (int i = 0; i < m; ++i) {
		int a, b, c;
		cin >> a >> b >> c;
		--a, --b;
		g[a].pb ({b, c});
		g[b].pb ({a, c});
	}
	auto d = Dijkstra (s, n);
	vector<int> kek;
	queue<int> a;
	a.push (t);
	while (!a.empty ()) {
		int v = a.front ();
		kek.pb (v);
		a.pop ();
		for (auto& u: g[v]) {
			if (d[u.fi] + u.se == d[v]) {
				G[v].pb (u.fi);
				if (!used[u.fi]) {
					a.push (u.fi);
					used[u.fi] = 1;
				}
			}
		}
	}
	for (auto& x: kek) {
		dbg (x + 1);
		for (auto& ch: G[x]) {
			dbg (ch + 1);
		}
	}
	int ans = 1e18;
	{
		for (auto& x: used) x = 0;
		d = Dijkstra (u, n);
		chkmin (ans, d[v]);
		dbg (ans);
		for (auto& x: kek) {
			if (!used[x]) calc (x, d);
			dbg (x + 1);
			dbg (dp[x]);
		}
		d = Dijkstra (v, n);
		for (auto& x: kek) {
			chkmin (ans, d[x] + dp[x]);
			dbg (x + 1);
			dbg (ans);
		}
	}
	{
		swap (v, u);
		for (auto& x: used) x = 0;
		d = Dijkstra (u, n);
		chkmin (ans, d[v]);
		// dbg (ans);
		for (auto& x: kek) {
			if (!used[x]) calc (x, d);
			// dbg (x + 1);
			// dbg (dp[x]);
		}
		d = Dijkstra (v, n);
		for (auto& x: kek) {
			chkmin (ans, d[x] + dp[x]);
			// dbg (x + 1);
			// dbg (ans);
		}
	}
	cout << ans << '\n';






}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:146:14: warning: unused variable 'ch' [-Wunused-variable]
  146 |   for (auto& ch: G[x]) {
      |              ^~

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