Submission #662634

#	Time	Username	Problem	Language	Result	Execution time	Memory
662634		Ninja_Kunai	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	486 ms	28224 KiB

commuter_pass

/**
*    Author :  Nguyen Tuan Vu
*    Created : 26.11.2022
**/

#pragma GCC optimize("O2")
#pragma GCC target("avx,avx2,fma")
#include<bits/stdc++.h>
#define MASK(x) ((1)<<(x))
#define BIT(x, i) (((x)>>(i))&(1))
#define ALL(v)  (v).begin(), (v).end()
#define REP(i, n)  for (int i = 0, _n = (n); i < _n; ++i)
#define FOR(i, a, b)  for (int i = (a), _b = (b); i <= _b; ++i) 
#define FORD(i, b, a)  for (int i = (b), _a = (a); i >= _a; --i)
#define db(val) "["#val" = "<<(val)<<"] "
#define TIME  (1.0 * clock() / CLOCKS_PER_SEC)

template <class X, class Y> bool minimize(X &a, Y b) {
    if (a > b) return a = b, true;
    return false;
}
template <class X, class Y> bool maximize(X &a, Y b) {
    if (a < b) return a = b, true;
    return false;
}

using namespace std;

mt19937 jdg(chrono::steady_clock::now().time_since_epoch().count());
int Rand(int l, int r) {return l + jdg() % (r - l + 1);}

void file(){
    #define TASK "TASK"
    if(fopen(TASK".in", "r")) {
        freopen(TASK".in", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
}

const int N = 1e5 + 5;
int n, m, st[2], en[2];
long long dp[2][N], f[N][2][2], ans;
vector <pair <int, int>> adj[N];

void dijkstra(int x, long long dp[]) {
	FOR(i, 1, n) dp[i] = 1e18 + 7;
	priority_queue <pair <long long, int>, vector <pair <long long, int>>, greater <pair <long long, int>>> heap;
	heap.push({dp[x] = 0, x});

	while (heap.size()) {
		auto [du, u] = heap.top();
		heap.pop();

		if (du != dp[u]) continue;
		for (auto v : adj[u]) if (minimize(dp[v.second], dp[u] + v.first)) {
			heap.push({dp[v.second], v.second});
		}
	}
}

bool check(int u, int w, int v, int type) {
	if (type == 0)
		return (dp[0][u] + w + dp[1][v] == dp[0][en[0]]);
	return (dp[0][v] + w + dp[1][u] == dp[0][en[0]]);
}

void dijkstra2(int mask) {
    FOR(i, 1, n) REP(j, 2) REP(k, 2) f[i][j][k] = 1e18 + 7;
    #define iii pair <long long, tuple <int, int, int>>
    priority_queue <iii, vector <iii>, greater <iii>> heap;
    heap.push({f[st[1]][0][0] = 0, {st[1], 0, 0}});

    //cout << check(1, 1, 2) << '\n';

    while (heap.size()) {
    	auto [du, tmp] = heap.top();
    	auto [u, type, type2] = tmp;
    	heap.pop();
    	if (du != f[u][type][type2]) continue;
    	//cout << u << ' ' << type << ' ' << type2 << ' ' << f[u][type][type2] << '\n';
    	for (auto v : adj[u]) {
    		if (type == 0) {
    			if (minimize(f[v.second][type][type2], f[u][type][type2] + v.first)) {
    				heap.push({f[v.second][type][type2], {v.second, type, type2}});
    			}

    			if (check(u, v.first, v.second, mask)) {
    				if (minimize(f[v.second][1][1], f[u][type][type2])) {
    					heap.push({f[v.second][1][1], {v.second, 1, 1}});
    				}
    			}
    		}
    		else {
    			if (type2 == 0) {
	    			if (minimize(f[v.second][type][type2], f[u][type][type2] + v.first)) {
	    				heap.push({f[v.second][type][type2], {v.second, type, type2}});
	    			}
    			}
    			else {
 	    			if (minimize(f[v.second][type][0], f[u][type][type2] + v.first)) {
	    				heap.push({f[v.second][type][0], {v.second, type, 0}});
	    			}

	    			if (check(u, v.first, v.second, mask)) {
	    				if (minimize(f[v.second][1][1], f[u][type][type2])) {
	    					heap.push({f[v.second][1][1], {v.second, 1, 1}});
	    				}
	    			}
    			}
    		}
    	}
    }

    minimize(ans, min({f[en[1]][0][0], f[en[1]][1][0], f[en[1]][1][1]}));
}

int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    file();
    ans = 1e18 + 7;
    cin >> n >> m;
    cin >> st[0] >> en[0];
    cin >> st[1] >> en[1];
    FOR(i, 1, m) {
    	int u, v, w; cin >> u >> v >> w;
    	adj[u].push_back({w, v});
    	adj[v].push_back({w, u});
    }

    dijkstra(st[0], dp[0]);
    dijkstra(en[0], dp[1]);

    //FOR(i, 1, n) cout << dp[0][i] << ' ' << dp[1][i] << '\n';

    dijkstra2(0);
    dijkstra2(1);
    cout << ans;

    cerr << "Time elapsed: " << TIME << " s.\n";
    return 0;
}

/*
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INPUT:                                            |
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OUTPUT:                                           |
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*/

Compilation message (stderr)

commuter_pass.cpp: In function 'void file()':
commuter_pass.cpp:35:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |         freopen(TASK".in", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:36:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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