Submission #1020758

#	Time	Username	Problem	Language	Result	Execution time	Memory
1020758		Unforgettablepl	Reconstruction Project (JOI22_reconstruction)	C++17	42 / 100	5089 ms	5816 KiB

reconstruction

#pragma GCC optimize("Ofast","unroll-loops")
#include <bits/stdc++.h>
using namespace std;

#define int long long

const int INF = 1e15;

struct UFDS{
	vector<int> p,siz;
	UFDS(int n):p(n+1),siz(n+1,1){iota(p.begin(),p.end(),0);}
	int findRoot(int x){
		return p[x]==x ? x : p[x]=findRoot(p[x]);
	}
	bool unite(int a,int b){
		a = findRoot(a);
		b = findRoot(b);
		if(a==b)return false;
		if(siz[a]<siz[b])swap(a,b);
		siz[a]+=siz[b];
		p[b]=a;
		return true;
	}
};

int32_t main(){
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	int n,m;
	cin >> n >> m;
	vector<pair<int,pair<int,int>>> edges(m);
	for(auto&[a,b]:edges)cin>>b.first>>b.second>>a;
	sort(edges.begin(),edges.end());
	vector<set<pair<int,int>>> adj;
	vector<int> replaces_front(m,-1);
	{
		// Calculation from the front
		adj = vector<set<pair<int,int>>>(n+1);
		int tar;
		function<pair<bool,int>(int,int)> dfs = [&](int x,int p){
			if(x==tar)return make_pair(true,(int)1e15);
			for(auto[v,i]:adj[x])if(v!=p){
				auto res = dfs(v,x);
				if(res.first)return make_pair(true,min(res.second,i));
			}
			return make_pair(false,(int)0);
		};
		for(int i=0;i<m;i++){
			tar = edges[i].second.second;
			auto res = dfs(edges[i].second.first,-1);
			if(res.first){
				adj[edges[res.second].second.first].erase({edges[res.second].second.second,res.second});
				adj[edges[res.second].second.second].erase({edges[res.second].second.first,res.second});
				replaces_front[i] = res.second;
			}
			adj[edges[i].second.first].insert({edges[i].second.second,i});
			adj[edges[i].second.second].insert({edges[i].second.first,i});
		}
	}
	vector<int> replaces_back(m,-1);
	{
		// Calculation from the back
		adj = vector<set<pair<int,int>>>(n+1);
		int tar;
		function<pair<bool,int>(int,int)> dfs = [&](int x,int p){
			if(x==tar)return make_pair(true,(int)-1);
			for(auto[v,i]:adj[x])if(v!=p){
				auto res = dfs(v,x);
				if(res.first)return make_pair(true,max(res.second,i));
			}
			return make_pair(false,(int)0);
		};
		for(int i=m-1;i>=0;i--){
			tar = edges[i].second.second;
			auto res = dfs(edges[i].second.first,-1);
			if(res.first){
				adj[edges[res.second].second.first].erase({edges[res.second].second.second,res.second});
				adj[edges[res.second].second.second].erase({edges[res.second].second.first,res.second});
				replaces_back[i] = res.second;
			}
			adj[edges[i].second.first].insert({edges[i].second.second,i});
			adj[edges[i].second.second].insert({edges[i].second.first,i});
		}
	}
	set<int> curr_left;
	set<int> curr_right;
	for(auto&i:adj)for(auto[a,b]:i)curr_right.insert(b);
	auto solve = [&](int x){
		vector<pair<int,int>> curredges;
		for(int i:curr_left){
			curredges.emplace_back(abs(edges[i].first-x),i);
		}
		for(int i:curr_right){
			curredges.emplace_back(abs(edges[i].first-x),i);
		}
		sort(curredges.begin(),curredges.end());
		int ans = 0;
		UFDS dsu(n);
		for(auto[c,i]:curredges){
			if(dsu.unite(edges[i].second.first,edges[i].second.second))ans+=c;
		}
		return ans;
	};
	int iter = 0;
	int q;
	cin >> q;
	for(int i=1;i<=q;i++){
		int query;
		cin >> query;
		while(iter!=m and edges[iter].first<query){
			curr_right.erase(iter);
			if(replaces_back[iter]!=-1){
				curr_right.insert(replaces_back[iter]);
			}
			curr_left.insert(iter);
			if(replaces_front[iter]!=-1){
				curr_left.erase(replaces_front[iter]);
			}
			iter++;
		}
		cout << solve(query) << '\n';
	}
}

• Subtask 1: 3 / 3
• Subtask 2: 4 / 4
• Subtask 3: 0 / 7
• Subtask 4: 0 / 28
• Subtask 5: 35 / 35
• Subtask 6: 0 / 23