Submission #228246

#	Time	Username	Problem	Language	Result	Execution time	Memory
228246		ryansee	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	528 ms	22248 KiB

commuter_pass

#include "bits/stdc++.h"
using namespace std;

#define FAST ios_base::sync_with_stdio(false); cin.tie(0);
#define pb push_back
#define eb emplace_back
#define ins insert
#define f first
#define s second
#define cbr cerr << "hi\n"
#define mmst(x, v) memset((x), v, sizeof ((x)))
#define siz(x) ll(x.size())
#define all(x) (x).begin(), (x).end()
#define lbd(x,y) (lower_bound(all(x),y)-x.begin())
#define ubd(x,y) (upper_bound(all(x),y)-x.begin())
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());    //can be used by calling rng() or shuffle(A, A+n, rng)
inline long long rand(long long x, long long y) { return (rng() % (y+1-x)) + x; } //inclusivesss
string inline to_string(char c) {string s(1,c);return s;} template<typename T> inline T gcd(T a,T b){ return a==0?llabs(b):gcd(b%a,a); }

typedef long long ll; 
typedef long double ld;
#define FOR(i,s,e) for(ll i=s;i<=ll(e);++i)
#define DEC(i,s,e) for(ll i=s;i>=ll(e);--i)
typedef pair<ll,ll>pi; typedef pair<ll,pi>spi; typedef pair<pi,pi>dpi;

#define LLINF ((long long)1e18)
#define INF int(1e9+1e6)
#define MAXN (100006)
ll n,m,U,V,S,T,dist[MAXN],dist2[MAXN],best[2][MAXN],mi[2][MAXN],ans=LLINF;
vector<pi>v[MAXN];
int main(){
	cin>>n>>m>>S>>T>>U>>V;
	FOR(i,0,m-1){
		ll a,b,c;cin>>a>>b>>c;
		v[a].eb(b,c),v[b].eb(a,c);
	}
	priority_queue<pi,vector<pi>,greater<pi>> pq;
	mmst(dist,-1);
	dist[T]=0, pq.emplace(0,T);
	while(pq.size()){
		ll x=pq.top().s,d=pq.top().f; pq.pop();
		if(dist[x]^d)continue;
		for(auto i:v[x])if(dist[i.f]==-1||dist[i.f]>d+i.s){
			dist[i.f]=d+i.s;
			pq.emplace(dist[i.f],i.f);
		}
	}
	FOR(i,1,n)assert(~dist[i]);//dist[i] will nvr be -1
	// have to set ans to be shortest dist between U and V
	for(auto sp:{U,V}){
		assert(pq.empty());
		ll alt = sp == U ? 0 : 1;
		mmst(best[alt],-1);
		best[alt][sp]=0, pq.emplace(0,sp);
		while(pq.size()){
			ll x=pq.top().s,d=pq.top().f;
			pq.pop();
			if(best[alt][x]^d)continue;
			for(auto i:v[x])if(best[alt][i.f]==-1||best[alt][i.f]>d+i.s){
				best[alt][i.f]=d+i.s;
				pq.emplace(best[alt][i.f],i.f);
			}
		}
		ans=best[alt][sp==U?V:U];
	}
	assert(pq.empty());
	mmst(dist2,-1);
	dist2[S]=0, mi[0][S]=best[0][S], mi[1][S]=best[1][S], pq.emplace(0,S);
	while(pq.size()){
		ll x=pq.top().s,d=pq.top().f;
		pq.pop();
		if(dist2[x]^d)continue;
		for(auto i:v[x])if(dist2[i.f]==-1||dist2[i.f]>=d+i.s){
			if(dist[i.f] + d + i.s == dist[S]) {
				ll keep0=LLINF,keep1=LLINF;
				if(dist2[i.f]!=d+i.s) dist2[i.f]=d+i.s, pq.emplace(dist2[i.f],i.f);
				else keep0=mi[0][i.f],keep1=mi[1][i.f];
				ans=min(ans,mi[0][x]+best[1][i.f]);
				ans=min(ans,mi[1][x]+best[0][i.f]);
				mi[0][i.f]=min({mi[0][x], best[0][i.f],keep0});
				mi[1][i.f]=min({mi[1][x], best[1][i.f],keep1});
			}
		}
	}
	cout<<ans<<'\n';
}

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