Submission #1312912

#	Time	Username	Problem	Language	Result	Execution time	Memory
1312912		herominhsteve	Village (BOI20_village)	C++20	100 / 100	57 ms	16704 KiB

Village

#include <bits/stdc++.h>
#define el '\n'
#define FNAME "village"
#define allof(x) x.begin(),x.end()
#define allof1(x) x.begin()+1,x.end()
#define mset(x,n) memset(x,(n),sizeof(x))
using namespace std;
const long long MOD = (long long) 1e9 + 7;
template<class X,class Y> bool minimize(X &a,Y b){ if (a>b) {a=b; return true;} return false;}
template<class X,class Y> bool maximize(X &a,Y b){ if (a<b) {a=b; return true;} return false;}

void setup(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
	if (fopen(FNAME".inp","r")){
		freopen(FNAME".inp","r",stdin);
		freopen(FNAME".out","w",stdout);
	}
}

const int MAXN = 1e5 + 5;
const long long INF = (long long) 1e16 + 15092007;

int n;
vector<int> graph[MAXN];

void init(){
	cin>>n;
	for (int i=1;i<n;i++){
		int u,v;
		cin>>u>>v;
		graph[u].push_back(v);
		graph[v].push_back(u);
	}
}

namespace calMin{
	long long res = 0;
	vector<int> des;
	void dfs(int u=1,int pre=-1){
		for (int v : graph[u]){
			if (v==pre) continue;
			dfs(v,u);
			if (des[v] == v){
				swap(des[u],des[v]);
				res += 2;
			}
		}
		if (pre==-1 and des[u]==u and !graph[u].empty()){
			swap(des[u],des[graph[u].front()]);
			res += 2;
		}
	}
	
	void getAns(){
		des.assign(n+1,0);
		iota(allof(des),0);
		dfs();
	}

};

namespace calMax{
	int sz[MAXN];
	void dfsSZ(int u=1,int pre=-1){
		sz[u] = 1;
		for (int v : graph[u]){
			if (v==pre) continue;
			dfsSZ(v,u);
			sz[u] += sz[v];
		}
	}
	
	int dfsCentroid(int u=1,int pre=-1){
		for (int v : graph[u]){
			if (v==pre) continue;
			if (sz[v] * 2 > n) return dfsCentroid(v,u);
		}
		return u;
	}

	int centroid; 
	long long res = 0;
	vector<int> des;

	int timedfs;
	int in[MAXN];
	vector<int> euler;

	void dfsEuler(int u,int pre){
		euler.push_back(u);
		in[u] = timedfs++;
		for (int v : graph[u]){
			if (v==pre) continue;
			dfsEuler(v,u);
		}
	}

	void getAns(){
		dfsSZ();
		centroid = dfsCentroid();
		for (int u=2;u<=n;u++)
			res += 2ll * min(sz[u],n - sz[u]);
		dfsEuler(centroid,-1);
		des.assign(n+1,0);
		for (int u=1;u<=n;u++)
			des[u] = euler[(in[u] + n/2) % n];	
	}

};

void sol(){
	calMin::getAns();
	calMax::getAns();
	cout<<calMin::res<<" "<<calMax::res<<el;
	for (int i=1;i<=n;i++) cout<<calMin::des[i]<<" ";
	cout<<el;
	for (int i=1;i<=n;i++) cout<<calMax::des[i]<<" ";
}

int main(){
    setup();
    init();
    sol();
}

Compilation message (stderr)

Village.cpp: In function 'void setup()':
Village.cpp:16:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |                 freopen(FNAME".inp","r",stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
Village.cpp:17:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |                 freopen(FNAME".out","w",stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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