Submission #731630

#	Time	Username	Problem	Language	Result	Execution time	Memory
731630		khshg	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	418 ms	30896 KiB

commuter_pass

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <unordered_set>
#include <vector>
using namespace std;
#define int long long

using ll = long long;
using ld = long double;
using str = string;

using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<ld, ld>;
#define mp make_pair
#define ff first
#define ss second

template<class T> using V = vector<T>;
#define arr array
using vi = V<int>;
using vb = V<bool>;
using vl = V<ll>;
using vd = V<ld>;
using vs = V<str>;
using vpi = V<pi>;
using vpl = V<pl>;
using vpd = V<pd>;

#define sz(x) (int)((x).size())
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) (x).rbegin(), (x).rend()
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert
#define pb push_back
#define eb emplace_back
#define ft front()
#define bk back()

#define lb lower_bound
#define ub upper_bound

#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for(int i = (b) - 1; i >= (a); --i)
#define R0F(i, a) ROF(i, 0, a)
#define rep(a) F0R(_, a)
#define trav(a, x) for(auto& a : x)

template<class T> bool ckmin(T& a, const T& b) { return (b < a ? a = b, 1 : 0); }
template<class T> bool ckmax(T& a, const T& b) { return (b > a ? a = b, 1 : 0); }

const ll INF = 0x3f3f3f3f3f3f3f3f;
const int maxn = 100000;
vpi adj[maxn];
vi par[maxn];
int N, M;
int S, T;
int U, Vv;
ll ans;
vl fromU, fromV;

void dijkstra(int st, vl& dis) {
	dis = vl(N, INF);
	priority_queue<pl> pq;
	pq.push({dis[st] = 0, st});
	while(sz(pq)) {
		ll D; int cur;
		tie(D, cur) = pq.top(); pq.pop();
		D *= -1LL;
		if(dis[cur] < D) {
			continue;
		}
		trav(u, adj[cur]) {
			if(dis[u.ff] > D + u.ss) {
				pq.push({-(dis[u.ff] = D + u.ss), u.ff});
			}
		}
	}
}

void dfs(int s, V<arr<ll, 2>>& dp) {
	dp[s][0] = fromU[s];
	dp[s][1] = fromV[s];
	trav(u, par[s]) {
		if(dp[u][0] == INF && dp[u][1] == INF) {
			dfs(u, dp);
		}
		ckmin(dp[s][0], dp[u][0]);
		ckmin(dp[s][1], dp[u][1]);
	}
}

V<arr<ll, 2>> pp(int st, int en) {
	vl dis(N, INF);
	priority_queue<pl> pq;
	pq.push({dis[st] = 0, st});
	par[st].clear();
	while(sz(pq)) {
		ll D; int cur;
		tie(D, cur) = pq.top(); pq.pop();
		D *= -1LL;
		if(dis[cur] < D) {
			continue;
		}
		trav(u, adj[cur]) {
			if(dis[u.ff] > D + u.ss) {
				pq.push({-(dis[u.ff] = D + u.ss), u.ff});
				par[u.ff].clear();
			}
			if(dis[u.ff] == D + u.ss) par[u.ff].eb(cur);
		}
	}
	V<arr<ll, 2>> dp(N, arr<ll, 2>{INF, INF}); // 0 -> U; 1 -> V;
	dfs(en, dp);
	return dp;
}

int32_t main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cin >> N >> M;
	cin >> S >> T;
	cin >> U >> Vv;
	--S; --T; --U; --Vv;
	rep(M) {
		int A, B, C; cin >> A >> B >> C;
		--A; --B;
		adj[A].eb(B, C);
		adj[B].eb(A, C);
	}
	dijkstra(U, fromU);
	dijkstra(Vv, fromV);
	ans = fromU[Vv];
	V<arr<ll, 2>> fS = pp(S, T);
	V<arr<ll, 2>> fT = pp(T, S);
	F0R(i, N) {
		ckmin(ans, fS[i][0] + fT[i][1]);
		ckmin(ans, fS[i][1] + fT[i][0]);
	}
	cout << ans << '\n';
	return 0;
}

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