Submission #253869

#	Time	Username	Problem	Language	Result	Execution time	Memory
253869		super_j6	Cities (BOI16_cities)	C++14	14 / 100	6050 ms	111216 KiB

cities

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <string.h>
#include <vector>
#include <set>
using namespace std;
#define endl '\n'
#define ll long long
#define pi pair<ll, ll>
#define f first
#define s second
 
ll inf = 0x3f3f3f3f3f3f3f3f;
const int mxn = 100000, mxk = 6;
int n, m, k;
int a[mxk], s[mxk];
ll dd[mxn], vis[mxn];
vector<ll> d[mxn], p[mxn];
vector<pi> g[mxn];
set<pi> pq;
 
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n >> k >> m;
	
	for(int i = 0; i < k; i++){
		cin >> a[i];
		a[i]--;
	}
 
	for(int i = 0; i < m; i++){
		int u, v, w;
		cin >> u >> v >> w;
		u--, v--;
		g[u].push_back({v, w});
		g[v].push_back({u, w});
	}
	
	for(int s = 0; s < n; s++){
		if(k > 4 || count(a, a + k, s)){
			d[s].assign(n, inf);
			p[s].assign(n, -1);
			d[s][s] = 0;
			pq.insert({0, s});
			while(!pq.empty()){
				int c = pq.begin()->s;
				pq.erase(pq.begin());
				for(pi i : g[c]){
					if(d[s][c] + i.s < d[s][i.f]){
						pq.erase({d[s][c], i.f});
						pq.insert({d[s][i.f] = d[s][c] + i.s, i.f});
						p[s][i.f] = c;
					}
				}
			}
		}
	}
	
	ll ret = inf;
	if(k <= 3){
		for(int i = 0; i < n; i++){
			ll cur = 0;
			for(int j = 0; j < k; j++){
				cur += d[a[j]][i];
			}
			ret = min(ret, cur);
		}
	}else if(k == 4){
		for(int i = 0; i < n; i++){
			ll cur = 0;
			for(int j = 0; j < k; j++){
				cur += d[a[j]][i];
			}
			ret = min(ret, cur);
		}
		for(int s1 = 0; s1 < k; s1++)
		for(int s2 = 0; s2 < s1; s2++){
			ll s3 = -1, s4 = -1;
			for(int i = 0; i < k; i++){
				if(s1 != i && s2 != i){
					if(!~s3) s3 = i;
					else s4 = i;
				}
			}
			ll cur = d[a[s1]][a[s2]] + d[a[s3]][a[s4]];
			memset(dd, inf, sizeof(dd));
			memset(vis, 0, sizeof(vis));
			for(int i = a[s2]; ~i; i = p[a[s1]][i]){
				dd[i] = 0;
				pq.insert({0, i});
			}
			for(int i = a[s4]; ~i; i = p[a[s3]][i]) vis[i] = 1;
			while(!pq.empty()){
				int c = pq.begin()->s;
				pq.erase(pq.begin());
				if(vis[c]){
					cur += dd[c];
					while(!pq.empty()) pq.erase(pq.begin());
					break;
				}
				for(pi i : g[c]){
					if(dd[c] + i.s < dd[i.f]){
						pq.erase({dd[c], i.f});
						pq.insert({dd[i.f] = dd[c] + i.s, i.f});
					}
				}
			}
			ret = min(ret, cur);
		}
	}else{
		s[0] = 1;
		for(int i = 1; i <= k; i++) s[i] = 3 * s[i - 1];
		
		for(int i[3] = {0}; i[0] < n; i[0]++)
		for(i[1] = 0; i[1] < n; i[1]++)
		for(i[2] = 0; i[2] < n; i[2]++)
		for(int j = 0; j < s[k]; j++){
			ll cur = inf;
			for(int l = 0; l < n; l++) cur = min(cur, d[i[0]][l] + d[i[1]][l] + d[i[2]][l]);
			for(int l = 0; l < k; l++){
				cur += d[a[l]][i[j / s[l] % 3]];
			}
			ret = min(ret, cur);
		}
	}
	
	cout << ret << endl;
 
	return 0;
}

• Subtask 1: 0 / 22
• Subtask 2: 14 / 14
• Subtask 3: 0 / 15
• Subtask 4: 0 / 23
• Subtask 5: 0 / 26