Submission #392826

#	Time	Username	Problem	Language	Result	Execution time	Memory
392826		knightron0	Evacuation plan (IZhO18_plan)	C++14	100 / 100	905 ms	227984 KiB

plan

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

#define pb push_back
#define fr first
#define sc second
#define clr(a, x) memset(a, x, sizeof(a))
#define dbg(x) cout<<"("<<#x<<"): "<<x<<endl;
#define printvector(arr) for (auto it = arr.begin(); it != arr.end(); ++it) cout<<*it<<" "; cout<<endl;
#define all(v) v.begin(), v.end()
#define lcm(a, b) (a * b)/__gcd(a, b)
#define int long long int
#define printvecpairs(vec) for(auto it: vec) cout<<it.fr<<' '<<it.sc<<endl;
#define endl '\n'
#define pii pair<int, int>
#define float long double

const int MOD = 1e9 + 7;
const int INF = 2e15;
const int MAXN = 1e5 + 5;

int n, m, k, l;
vector<pii> adj[MAXN];
vector<int> mst[MAXN];
int dist[MAXN], b[MAXN], up[MAXN][100], tout[MAXN], tin[MAXN], upmn[MAXN][100], depth[MAXN];
int timer = 0;

void dfs(int v, int p, int d = 0){
	timer++;
	tin[v] = timer;
	up[v][0] = p;
	upmn[v][0] = min(dist[v], dist[p]);
	for(int i=1;i<=l;i++){
		up[v][i] = up[up[v][i-1]][i-1];
		upmn[v][i] = min(upmn[up[v][i-1]][i-1], upmn[v][i-1]);
	}
	depth[v] = d;
	for(int u: mst[v]){
		if(u != p){
			dfs(u, v, d+1);
		}
	}
	timer++;
	tout[v] = timer;
}

bool isanc(int a, int b){
	return tin[a] <= tin[b] && tout[a] >= tout[b];
}
int lca(int u, int v){
	if(isanc(u, v)) return u;
	if(isanc(v, u)) return v;
	for(int i = l;i >= 0;i--){
        if(!isanc(up[u][i], v)){
            u = up[u][i];
        }
    }
    return up[u][0];
}

int getmn(int u, int kx){
	int ans = dist[u];
	for(int i= 0;i<=l;i++){
		if(kx & (1<<i)){
			ans = min(ans, upmn[u][i]);
			u = up[u][i];
		}
	}
	return ans;
}

void dstra(){
	for(int i=1;i<=n;i++){
		dist[i] = INF;
	}
	priority_queue<pii> pq;
	for(int j= 1;j<=k;j++){
		dist[b[j]] = 0;
		pq.push({0, b[j]});
	}
	while(!pq.empty()){
		int u = pq.top().sc;
		pq.pop();
		for(auto e: adj[u]){
			int w = e.sc, v = e.fr;
			if(dist[u]+w < dist[v]){
				dist[v] = dist[u] + w;
				pq.push({-dist[v], v});
			}
		}
	}
}


int parent[MAXN] = {-1};

void init(){
    for(int i= 1;i<=n;i++) parent[i] = i;
    timer = 0;
	clr(tout, 0);
	clr(tin, 0);
	l = ceil(log2(n));	
	clr(up, 0);
}

int find_set(int s){
    if(s == parent[s]){
        return s;
    }
    return parent[s] = find_set(parent[s]);
}

bool union_sets(int a, int b){
    a = find_set(a);
    b = find_set(b);
    if(a != b){
        parent[b] = a;
        return true;
    } else {
    	return false;
    }
}


signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    #ifdef LOCAL
    freopen("input.txt", "r", stdin);
    #endif
	cin>>n>>m;
	vector<pii> edges;
	for(int i=0;i<m;i++){
		int u, v, w;
		cin>>u>>v>>w;
		adj[u].pb({v, w});
		adj[v].pb({u, w});
		edges.pb({u, v});
	}
	cin>>k;
	for(int i= 1;i<=k;i++){
		cin>>b[i];
	}
	dstra();
	init();
	vector<pair<int, pii>> wedges;
	for(auto edge: edges){
		wedges.pb({min(dist[edge.fr], dist[edge.sc]), {edge}});
	}
	sort(all(wedges));
	reverse(all(wedges));
	for(auto edge: wedges){
		int u = edge.sc.fr, v = edge.sc.sc;
		if(union_sets(u, v)){
			mst[v].pb(u);
			mst[u].pb(v);
		}
	}
	dfs(1, 1);
	int q;
	cin>>q;
	while(q--){
		int u, v;
		cin>>u>>v;
		int lc = lca(u, v);
		int du = depth[u]-depth[lc];
		int dv = depth[v]-depth[lc];
		cout<<min(getmn(u, du), getmn(v, dv))<<endl;

	}
    return 0;
}

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