Submission #682872

#	Time	Username	Problem	Language	Result	Execution time	Memory
682872		iskhakkutbilim	Evacuation plan (IZhO18_plan)	C++14	10 / 100	4057 ms	11104 KiB

plan

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

//#define int long long
#define ff first
#define ss second
#define all(a) a.begin(), a.end()
const int N = 1e5;
const int M = 1e9;
int n, m, k;
vector< pair<int, int> > g[N];

int AEC[N], distanc[N];
vector<int> A, B;
priority_queue< pair<int, int> > q;

void dijkstra(int start, vector<int>&dis){
	for(int i = 0;i < n; i++) dis[i] = (i == start ? 0 : M);
	q.push({dis[start], start});
	while(!q.empty()){
		int v = q.top().ss, D = q.top().ff;
		q.pop();
		if(D > dis[v]) continue;
		for(auto [to, len] : g[v]){
			if(dis[to] > dis[v] + len){
				dis[to] = dis[v]+len;
				q.push({dis[to], to});
				
				if(AEC[start]==0 and AEC[to] == 1){
					distanc[start] = min(distanc[start], dis[to]);
				}
				if(AEC[start]==1 and AEC[to] == 0){
					distanc[to] = min(distanc[to], dis[to]);
				}
			}
		}
	}
}


main(){
   ios::sync_with_stdio(0);
   cin.tie(0); cout.tie(0);
	cin >> n >> m;
	for(int i = 0;i < m; i++){
		int a, b, w; cin >> a >> b >> w;
		a--, b--;
		g[a].push_back({b, w});
		g[b].push_back({a, w});
	}
	vector<int> dis(n);
	cin >> k;
	for(int i = 0;i < k; i++){
		int a; cin >> a; a--;
		AEC[a] = 1;
	}
	for(int i = 0;i < n; i++){
		distanc[i] = M;
		if(AEC[i] == 0) B.push_back(i);
		else A.push_back(i);
	}
	if(k > (int)sqrt(n)){
		for(int start : B){
			dijkstra(start, dis);
		}
	}else{
		for(int start : A){
			dijkstra(start, dis);
		}
	}
	int Q; cin >> Q;
	if(n <= 15 and m <= 200 and Q <= 200){
		vector<vector<int>> dis1(n, vector<int>(n, -M));
		vector<int> used(n, 0), path;
		int s;
		path.push_back(0);
		function<void(int)> dfs=[&](int v){
			used[v] = 1;
			int mn = M;
			for(int i = path.size()-1; i >= 0; i--){
				if(AEC[path[i]] == 1) mn = 0;
				else
				mn = min(mn, distanc[path[i]]);
				dis1[path[i]][path.back()] = max(dis1[path[i]][path.back()], mn);
			}
			for(auto [to, len] : g[v]){
				if(used[to] == 0){
					path.push_back(to);
					dfs(to);
					path.pop_back();
				}
			}
			used[v] = 0;
		};
		dfs(0);
		while(Q--){
			int a, b; cin >> a >> b; a--, b--;
			if(dis1[a][b] == -M and dis1[b][a] == -M) assert(false);
			if(dis1[a][b] == -M) cout << dis1[b][a];
			else cout << dis1[a][b];
			cout << '\n';
		}
	}else{
		while(Q--){
			int a, b; cin >> a >> b; a--, b--;
			if(AEC[a] == 1 or AEC[b] == 1){
				cout << 0 << '\n';
			}else{
				cout << min(distanc[a], distanc[b]) << '\n';
			}
		}
	}
	return 0;
}

Compilation message (stderr)

plan.cpp: In function 'void dijkstra(int, std::vector<int>&)':
plan.cpp:24:12: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   24 |   for(auto [to, len] : g[v]){
      |            ^
plan.cpp: At global scope:
plan.cpp:41:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   41 | main(){
      | ^~~~
plan.cpp: In lambda function:
plan.cpp:86:13: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   86 |    for(auto [to, len] : g[v]){
      |             ^
plan.cpp: In function 'int main()':
plan.cpp:75:7: warning: unused variable 's' [-Wunused-variable]
   75 |   int s;
      |       ^

• Subtask 1: 10 / 10
• Subtask 2: 0 / 13
• Subtask 3: 0 / 12
• Subtask 4: 0 / 19
• Subtask 5: 0 / 46