Submission #940539

#	Time	Username	Problem	Language	Result	Execution time	Memory
940539		pcc	Village (BOI20_village)	C++17	100 / 100	77 ms	23240 KiB

Village

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

#define ll long long
#define pll pair<ll,ll>
#define pii pair<int,int>
#define fs first
#define sc second
#define tlll tuple<ll,ll,ll>


const int mxn = 1e5+10;
vector<int> tree[mxn];
int N;

namespace S1{
	ll ans;
	ll dp[mxn];
	int mx[mxn];
	void dfs(int now,int par){
		vector<int> need;
		dp[now] = 1;
		for(auto nxt:tree[now]){
			if(nxt == par)continue;
			dfs(nxt,now);
			if(dp[nxt])need.push_back(nxt);
		}
		if(need.size()>=2){
			dp[now] = 0;
			ans += need.size()*2;
			for(int i = 1;i<need.size();i++){
				mx[need[i-1]] = need[i];
			}
			mx[need.back()] = now;
			mx[now] = need[0];
			need.clear();
		}
		else if(need.size() == 1){
			dp[now] = 0;
			ans += 2;
			int a = need[0];
			mx[now] = a;
			mx[a] = now;
		}
		if(now==par&&dp[now]){
			ans += 2;
			int a = tree[now][0],b = mx[a];
			while(mx[b] != a)b = mx[b];
			mx[now] = a;
			mx[b] = now;
		}
		return;
	}
	void solve(){
		dfs(1,1);
		return;
	}
}

namespace S2{
	int mx[mxn],sz[mxn],dep[mxn];
	int arr[mxn];
	ll ans = 0;
	void szdfs(int now,int par){
		sz[now] = 1;
		for(auto nxt:tree[now]){
			if(nxt == par)continue;
			szdfs(nxt,now);
			sz[now] += sz[nxt];
		}
		return;
	}
	int get_centroid(int now,int par,int tar = sz[1]){
		for(auto nxt:tree[now]){
			if(nxt == par)continue;
			if(sz[nxt]>(tar-1)/2)return get_centroid(nxt,now,tar);
		}
		return now;
	}
	vector<vector<int>> v;
	vector<pii> vp;
	void dfs(int now,int par){
		dep[now] = dep[par]+1;
		ans += dep[now]*2;
		v.back().push_back(now);
		for(auto nxt:tree[now]){
			if(nxt == par)continue;
			dfs(nxt,now);
		}
		return;
	}
	void solve(){
		szdfs(1,1);
		int cen = get_centroid(1,1);
		for(auto nxt:tree[cen]){
			vp.push_back({0,v.size()});
			v.push_back({});
			dfs(nxt,cen);
			vp.back().fs = v.back().size();
		}
		sort(vp.begin(),vp.end());
		v[0].push_back(cen);
		vp[0].sc++;
		int pt = 0;
		while(!v.empty()){
			arr[pt] = v.back().back();
			v.back().pop_back();
			if(v.back().empty())v.pop_back();
			pt+=2;
			if(pt>=N)pt = 1;
		}
		for(int i = 0;i<N;i++)assert(arr[i]);
		for(int i = 1;i<N;i++){
			mx[arr[i]] = arr[i-1];
		}
		mx[arr[0]] = arr[N-1];
		return;
	}
}

int main(){
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin>>N;
	for(int i = 1;i<N;i++){
		int a,b;
		cin>>a>>b;
		tree[a].push_back(b);
		tree[b].push_back(a);
	}
	S1::solve();
	S2::solve();
	cout<<S1::ans<<' '<<S2::ans<<'\n';
	for(int i = 1;i<=N;i++)cout<<S1::mx[i]<<' ';cout<<'\n';
	for(int i = 1;i<=N;i++)cout<<S2::mx[i]<<' ';cout<<'\n';
	return 0;
}

Compilation message (stderr)

Village.cpp: In function 'void S1::dfs(int, int)':
Village.cpp:31:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |    for(int i = 1;i<need.size();i++){
      |                  ~^~~~~~~~~~~~
Village.cpp: In function 'int main()':
Village.cpp:133:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  133 |  for(int i = 1;i<=N;i++)cout<<S1::mx[i]<<' ';cout<<'\n';
      |  ^~~
Village.cpp:133:46: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  133 |  for(int i = 1;i<=N;i++)cout<<S1::mx[i]<<' ';cout<<'\n';
      |                                              ^~~~
Village.cpp:134:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  134 |  for(int i = 1;i<=N;i++)cout<<S2::mx[i]<<' ';cout<<'\n';
      |  ^~~
Village.cpp:134:46: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  134 |  for(int i = 1;i<=N;i++)cout<<S2::mx[i]<<' ';cout<<'\n';
      |                                              ^~~~

• Subtask 1: 12 / 12
• Subtask 2: 38 / 38
• Subtask 3: 50 / 50