Submission #911043

#	Time	Username	Problem	Language	Result	Execution time	Memory
911043		zhasyn	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	380 ms	36536 KiB

commuter_pass

#include <bits/stdc++.h>
#define pb push_back
#define pf push_front
using namespace std;
#define F first
#define S second
typedef long long ll;
#define pii pair <int, int>
#define pll pair <ll, ll>
typedef long double ld;
const ll N = 2 * 1e5 + 10;
const ll mod = 998244353;
 
ll um(ll a, ll b){
	return ((1LL * a * b) % mod + mod) % mod;
}
ll subr(ll a, ll b){
	return ((1LL * a - b) % mod + mod) % mod;
}

ll used[N], cnt[N], was[N], n, m;
vector <pll> q[N];
 
void create(ll from, ll to, vector <ll>&d){
	d[from] = 0;
  	set <pll> st;
  	st.insert({d[from], from});
  	while((ll)st.size() != 0){
  		auto [place, v] = *st.begin();
  		st.erase(st.begin());
  		if(d[v] != place) continue;
  		
  		for(auto u : q[v]){
  			if(d[u.F] == -1 || d[u.F] > d[v] + u.S){
  				d[u.F] = d[v] + u.S;
  				st.insert({d[u.F], u.F});
  			}
  		}
  	}
}
vector <ll> d, ans;
set <pll> st;
ll nw[N], mn[N];
void last(ll v){
	used[v] = true;
	if(nw[v] < ans[v]){
		ans[v] = nw[v];
		st.insert({ans[v], v});
	}
	for(auto u : q[v]){
		if(used[u.F]) continue;
		if(d[u.F] + u.S == d[v]) last(u.F);
	}
}
void prelast(int v){
	was[v] = true;
	for(auto u : q[v]){
		if(was[u.F]) continue;
		if(d[u.F] + u.S == d[v]) prelast(u.F);
	}
}
void dfs(ll v, ll dir){
	used[v] = true;
	mn[v] = min(mn[v], ans[v]);
	nw[v] = min(nw[v], mn[v]);
	for(auto u : q[v]){
      	if(used[u.F] || was[u.F] == 0) continue;
		if(d[v] + dir * u.S == d[u.F]){
			mn[u.F] = min(mn[u.F], mn[v]);
			if(--cnt[u.F] == 0) dfs(u.F, dir);
		}
	}
}
void calc(int v, int dir){
	for(ll i = 1; i <= n; i++){
		if(!was[i]) continue;
		for(auto u : q[i]){
			if(!was[u.F]) continue;
			if(d[u.F] == dir * u.S + d[i]) cnt[u.F]++;
		}
		mn[i] = LLONG_MAX;
	}
	dfs(v, dir);
	for(ll i = 1; i <= n; i++){
		used[i] = false;
		cnt[i] = 0;
	}
}
int main() {
	ios::sync_with_stdio(false);
  	cin.tie(NULL);
  	//freopen("bank.in", "r", stdin);
  	//freopen("bank.out", "w", stdout);
  	ll from, to, fir, sec;
  	cin >> n >> m >> from >> to >> fir >> sec;
  	for(ll i = 0, a, b, c; i < m; i++){
  		cin >> a >> b >> c;
  		q[a].pb({b, c});
  		q[b].pb({a, c});
  	}
  	vector <ll> d1, d2;
  	for(ll i = 0; i <= n; i++){
  		d1.pb(-1);
  		d2.pb(-1);
  		nw[i] = LLONG_MAX;
  	}
  	create(from, to, d1);
  	create(fir, sec, d2);
  	swap(d1, d);
  	swap(d2, ans);
  	prelast(to);
  	
  	
  	// for(int i = 1; i <= n; i++){
  		// cout << ans[i] << " ";
  	// }
  	// cout << endl;
  	calc(from, 1);
  	calc(to, -1);
  	
  	last(to);
  	while((ll)st.size() != 0){
  		auto [place, v] = *st.begin();
  		st.erase(st.begin());
  		if(ans[v] != place) continue;
  		
  		for(auto u : q[v]){
  			if(ans[u.F] == -1 || ans[u.F] > ans[v] + u.S){
  				ans[u.F] = ans[v] + u.S;
  				st.insert({ans[u.F], u.F});
  			}
  		}
  	}
  	cout << ans[sec];
  return 0;
}

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