Submission #916637

#	Time	Username	Problem	Language	Result	Execution time	Memory
916637		LCJLY	Love Polygon (BOI18_polygon)	C++14	100 / 100	213 ms	11952 KiB

polygon

#include <bits/stdc++.h>
using namespace std;
 
#define int long long
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << "  " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << "  " << j << " " << #i << "  " << q << " " << #p << endl; 
#define show4(x,y) for(auto it:x) cout << it << " "; cout << #y << endl;
typedef pair<int,int>pii;

int pp[100005];
map<string,int>mp;
int ptr=0;
int sz=0;
bool visited[100005];
int in[100005];

void dfs(int index){
	sz++;
	visited[index]=true;
	int nx=pp[index];
	if(visited[nx]) return;
	dfs(nx);
}


void solve(){
	int n;
	cin >> n;
	string s,s2;
	for(int x=0;x<n;x++){
		cin >> s >> s2;
		if(mp.find(s)==mp.end()){
			mp[s]=ptr++;
		}
		if(mp.find(s2)==mp.end()){
			mp[s2]=ptr++;
		}
		pp[mp[s]]=mp[s2];
		//show2(a,mp[s],b,mp[s2]);
		in[mp[s2]]++;
	}
	
	for(int x=0;x<n;x++){
		if(pp[pp[x]]==x&&pp[x]!=x){
			//relationship
			visited[x]=true;
			visited[pp[x]]=true;
		}
	}
	
	int counter=0;
	queue<int>q;
	for(int x=0;x<n;x++){
		if(in[x]==0) q.push(x);
	}
	while(!q.empty()){
		int cur=q.front();
		q.pop();
		if(visited[cur]) continue;
		int nx=pp[cur];
		//show2(cur,cur,nx,nx);
		if(visited[nx]){
			pp[cur]=cur;
			continue;
		}
		counter++;
		in[pp[nx]]--;
		if(in[pp[nx]]==0)q.push(pp[nx]);
		pp[nx]=cur;
		visited[nx]=true;
		visited[cur]=true;
	}
	
	for(int x=0;x<n;x++){
		if(visited[x]) continue;
		//show(visit,x);
		sz=0;
		dfs(x);
		if(sz==2) continue;
		counter+=(sz+1)/2;
	}
	if(n%2) cout << -1;
	else cout << counter;
}

int32_t main(){										
	ios::sync_with_stdio(0);	
	cin.tie(0);
	int t=1;
	//cin >> t;
	while(t--){
		solve();
	}
}

• Subtask 1: 21 / 21
• Subtask 2: 25 / 25
• Subtask 3: 29 / 29
• Subtask 4: 25 / 25