제출 #826399

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
826399		MohamedAliSaidane	Olympic Bus (JOI20_ho_t4)	C++14	100 / 100	296 ms	3532 KiB

ho_t4

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

typedef long long ll;

#define pb push_back
#define all(x) (x).begin(), (x).end()
#define ff first
#define ss second

const int nax = 205;
const int fax = 5e4 + 4;
const int INF = 1e9;
int n, m;
int seen[nax];
int sp1[nax], ps1[nax], sp2[nax], ps2[nax];
vector<int> adj[nax], rev_adj[nax];
int U[fax], V[fax], is_on_path[fax];
int C[fax];
ll D[fax];
int previ[nax][4];
int vis[nax][nax];

void calculate_sp(int up = -1, int vp = -1, int edg = -1)
{
	for(int i = 1; i <= n; i++)
	{
		sp1[i] = ps1[i] = sp2[i] = ps2[i] = INF;
		seen[i] = 0;
	}

	sp1[1] = ps1[1] = sp2[n] = ps2[n] = 0ll;
	previ[1][0] = previ[1][1] = -1;

	for(int loop = 1; loop <= n; loop++)
    {
        pair<int,int> E = {INF, n};
        for(int i = 1; i <= n; i++)
        {
            if(!seen[i] && sp1[i] < E.ff)
                E = {sp1[i], i};
        }
		int node = E.ss;
		if(seen[node])
			continue;
		seen[node] = 1;
		int path = E.ff;
		if(previ[node][0] != -1)
			is_on_path[previ[node][0]] = 1;
		for(auto e: adj[node])
		{
			if(e == edg)
				continue;
			int v = V[e];
			if(sp1[v] <= path + C[e])
				continue;
			sp1[v] = path + C[e];
			previ[v][0] = e;
		}
		if(node == vp)
		{
			int v = up;
			if(sp1[v] <= path + C[edg])
				continue;
			sp1[v] = path + C[edg];
		}
	}
	for(int i= 1; i <= n; i++)
		seen[i] = 0;

	for(int loop = 1; loop <= n; loop++)
    {
        pair<int,int> E = {INF, n};
        for(int i = 1; i <= n; i++)
        {
            if(!seen[i] && ps1[i] < E.ff)
                E = {ps1[i], i};
        }
		int node = E.ss;
		if(seen[node])
			continue;
		seen[node] = 1;
		int path = E.ff;
		if(previ[node][1] != -1)
			is_on_path[previ[node][1]] = 1;
		for(auto e: rev_adj[node])
		{
			if(e == edg)
				continue;
			int v = U[e];
			if(ps1[v] <= path + C[e])
				continue;
			ps1[v] = path + C[e];
		}
		if(node == up)
		{
			int v = vp;
			if(ps1[v] <= path + C[edg])
				continue;
			ps1[v] = path + C[edg];
		}
	}

	previ[n][2] = previ[n][3] = -1;
	for(int i =1; i <= n; i++)
		seen[i] = 0;

	for(int loop = 1; loop <= n; loop++)
    {
        pair<int,int> E = {INF, n};
        for(int i = 1; i <= n; i++)
        {
            if(!seen[i] && sp2[i] < E.ff)
                E = {sp2[i], i};
        }
		int node = E.ss;
		if(seen[node])
			continue;
		seen[node] = 1;
		int path = E.ff;
		if(previ[node][2] != -1)
			is_on_path[previ[node][2]] = 1;
		for(auto e: adj[node])
		{
			if(e == edg)
				continue;
			int v = V[e];
			if(sp2[v] <= path + C[e])
				continue;
			sp2[v] = path + C[e];
			previ[v][2] = e;
		}
		if(node == vp)
		{
			int v = up;
			if(sp2[v] <= path + C[edg])
				continue;
			sp2[v] = path + C[edg];
		}
	}
	for(int i =1; i <= n; i++)
		seen[i] = 0;

	for(int loop = 1; loop <= n; loop++)
    {
        pair<int,int> E = {INF, n};
        for(int i = 1; i <= n; i++)
        {
            if(!seen[i] && ps2[i] < E.ff)
                E = {ps2[i], i};
        }
		int node = E.ss;
		if(seen[node])
			continue;
		seen[node] = 1;
		int path = E.ff;
		if(previ[node][3] != -1)
			is_on_path[previ[node][3]] = 1;
		for(auto e: rev_adj[node])
		{
			if(e == edg)
				continue;
			int v = U[e];
			if(ps2[v] <= path + C[e])
				continue;
			ps2[v] = path + C[e];
			previ[v][3] = e;
		}
		if(node == up)
		{
			int v = vp;
			if(ps2[v] <= path + C[edg])
				continue;
			ps2[v] = path + C[edg];
		}

	}
	assert(sp1[1] == 0);
	assert(sp2[n] == 0);
	assert(sp1[n] == ps2[1]);
	assert(sp2[1] == ps1[n]);
}
void solve()
{
	cin >> n >> m;
	vector<pair<int,int>> VEC;
	for(int i = 0; i < m; i++)
	{
		cin >> U[i] >> V[i] >> C[i] >> D[i];
		VEC.pb({C[i], i});
	}
	sort(all(VEC));
	for(auto p: VEC)
	{
		int e = p.ss;
		if(vis[U[e]][V[e]] == 2)
			continue;
		adj[U[e]].pb(e);
		rev_adj[V[e]].pb(e);
		vis[U[e]][V[e]]++;
	}
	calculate_sp();
	vector<int> NON, YES;
	for(int i = 0; i < m; i++)
	{
		if(is_on_path[i])
			YES.pb(i);
		else
			NON.pb(i);
	}
	assert((int)(YES.size()) <= 4 * n);
	ll ans = sp1[n] >= INF || sp2[1] >= INF? 2ll * INF: sp1[n] + sp2[1];
	for(auto i: NON)
	{
		int u = U[i], v = V[i];
		ll c =  C[i], d = D[i];
		ll un = sp1[n];
		ll uV = sp1[v];
		ll Un = ps2[u];
		ll nu = sp2[1];
		ll nV = sp2[v];
		ll Uu = ps1[u];
		if((un >= INF && uV + c + Un >= INF) || (nu >= INF && nV + c + Uu >= INF))
				continue;
		ll rep = d + min(un, uV + c + Un) + min(nu, nV + c + Uu);
		ans = min(ans, rep);
	}
	for(auto i: YES)
	{

		calculate_sp(U[i], V[i], i);
		if(sp1[n] >= INF || sp2[1] >= INF)
			continue;
		ans = min(ans, (ll)(sp1[n]) + (ll)(sp2[1]) + D[i]);
		//cout << sp1[n] << ' ' << sp2[1] << '\n';
	}
	if(ans >= 2ll * INF)
		cout << "-1";
	else
		cout << ans;
}

int32_t main()
{
	ios::sync_with_stdio(false);
	cin.tie(0); cout.tie(0);

	int tt = 1; // cin >> tt;
	while(tt--)
		solve();
}

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