Submission #231639

#	Time	Username	Problem	Language	Result	Execution time	Memory
231639		_7_7_	Olympic Bus (JOI20_ho_t4)	C++14	100 / 100	682 ms	3064 KiB

ho_t4

#include <bits/stdc++.h>                                           
 
//#define int long long
//#pragma GCC optimize("Ofast")
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4")
 
 
#define file(s) freopen(s".in","r",stdin); freopen(s".out","w",stdout);
#define forev(i, b, a) for(int i = (b); i >= (a); --i)
#define forn(i, a, b) for(int i = (a); i <= (b); ++i)
#define all(x) x.begin(), x.end()
#define sz(s) (int)s.size()
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define s second
#define f first
 
 
using namespace std;
 
 
typedef pair < long long, long long > pll;    
typedef pair < int, int > pii;
typedef unsigned long long ull;         
typedef vector < pii > vpii;
typedef vector < int > vi;
typedef long double ldb;  
typedef long long ll;  
typedef double db;                             
 
 
const int inf = 1e9, maxn = 208, mod = 1e9 + 7, N = 5e4 + 11;
const int dx[] = {1, -1, 0, 0}, dy[] = {0, 0, 1, -1}, block = 555;
const pii base = mp(1171, 3307), Mod = mp(1e9 + 7, 1e9 + 9);
const db eps = 1e-12, pi = 3.14159265359;
const ll INF = 1e18;

int n, m, a[N], b[N], c[N], d[N], p[maxn], Bad, F[maxn][maxn], D[maxn]; 
priority_queue < pii, vpii, greater < pii > > q;
vpii g[2][maxn];
bool I[4][N];

 
 
void Floyd () {
	for (int i = 1; i <= n; ++i)
		for (int j = 1; j <= n; ++j)	
		    if (i != j)
				F[i][j] = inf;
 
	for (int i = 1; i <= m; ++i)
		F[a[i]][b[i]] = min(F[a[i]][b[i]], c[i]);
 
	for (int k = 1; k <= n; ++k)
		for (int i = 1; i <= n; ++i)
			for (int j = 1; j <= n; ++j)
				F[i][j] = min(F[i][j], F[i][k] + F[k][j]);
 
}
 
int Dijkstra (int s, int f, int j, int x = -1) {
	memset(p, -1, sizeof(p));

	for (int i = 1; i <= n; ++i)
		D[i] = inf;

	while (sz(q))
		q.pop();

	D[s] = 0;
	q.push(mp(0, s));
	while (sz(q)) {
		int v = q.top().s, w = q.top().f;
		if (Bad && v == f)
			return D[f];
		q.pop();

		if (w > D[v])
			continue;

		for (auto X : g[j][v]) {			
			int to = X.f, i = X.s;
			if (i != Bad && D[to] > D[v] + c[i]) {
				D[to] = D[v] + c[i];
				p[to] = i;
				q.push(mp(D[to], to));
			}
		}
	}

	if (x > -1) {
		for (int i = 1; i <= n; ++i)
			if (p[i] > -1)
				I[x][p[i]] = 1;
	}

	return inf;
}
 
 
main () {
	scanf("%d%d", &n, &m);
	for (int i = 1; i <= m; ++i) {
		scanf("%d%d%d%d", &a[i], &b[i], &c[i], &d[i]);
		g[0][a[i]].pb({b[i], i});
		g[1][b[i]].pb({a[i], i});
	}
 
	Floyd();
	Dijkstra(1, n, 0, 0);
	Dijkstra(n, 1, 0, 1);
	Dijkstra(1, n, 1, 2);
	Dijkstra(n, 1, 1, 3);
 


	int ans = inf + inf;
	if (F[1][n] < inf && F[n][1] < inf)
		ans = F[1][n] + F[n][1];

	for (int i = 1; i <= m; ++i) {
		Bad = i;
		g[0][b[i]].pb({a[i], m + 1});
		c[m + 1] = c[i];
	
		int d1, d2;
		if (I[0][i] || I[3][i])
			d1 = Dijkstra(1, n, 0);
		else
			d1 = min(F[1][n], F[1][b[i]] + F[a[i]][n] + c[i]);
		
		if (I[1][i] || I[2][i])
			d2 = Dijkstra(n, 1, 0);
		else
			d2 = min(F[n][1], F[n][b[i]] + F[a[i]][1] + c[i]);
		
		g[0][b[i]].ppb();
		if (d1 < inf && d2 < inf)
			ans = min(ans, d1 + d2 + d[i]);		
	}
 
	if (ans == inf + inf)
		ans = -1;
	printf("%d\n", ans);			
}

Compilation message (stderr)

ho_t4.cpp:103:7: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main () {
       ^
ho_t4.cpp: In function 'int main()':
ho_t4.cpp:104:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &m);
  ~~~~~^~~~~~~~~~~~~~~~
ho_t4.cpp:106:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d%d", &a[i], &b[i], &c[i], &d[i]);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 63 / 63