Submission #1281947

#	Time	Username	Problem	Language	Result	Execution time	Memory
1281947		ender_shayan	Love Polygon (BOI18_polygon)	C++20	100 / 100	165 ms	14216 KiB

polygon

#include <bits/stdc++.h>

using namespace std;

// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;

typedef long long ll;
typedef long double	ld;
typedef pair<int, int>	pii  ;
typedef pair<ll, ll>	pll  ;
typedef vector<pii>     vii  ;
typedef vector<int>     veci ;
typedef vector<pll>     vll  ;
typedef vector<ll>      vecll;

// find_by_order             order_of_key

//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define F		        first
#define S		        second
#define pb		        push_back
#define endl            '\n'
#define Mp		        make_pair
#define all(x)          x.begin(), x.end()
#define debug(x)        cerr << #x << " = " << x << endl
#define set_dec(x)	    cout << fixed << setprecision(x);
#define fast_io         ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io         freopen("in.txt" , "r" , stdin) ; freopen("out.txt" , "w" , stdout);
#define lb              lower_bound
#define ub              upper_bound
#define for1(n)         for(int i=1;i<=n;i++)
#define for0(n)         for(int i=0;i<n;i++)
#define forn(n)         for(int i=n;i>0;i--)
#define pq              priority_queue <pii, vector<pii>, greater<pii>>


const ll mod = 1e9+7 ;// 998244353 ;// 1e9+9;

ll inf=1e18;
const int N=1e6+100,L=21,bs=701;
int A[N],D[N],E[N],n,m,k,q,dp[N],pre[N],dist[N],vis[N],nn,deg[N];
vector<int>g[N];

map<string,int>B;
int main(){
    fast_io
    cin>>n;
    if(n%2==1)return cout<<"-1\n",0;
    for1(n){
        string a,b;cin>>a>>b;
        if(B[a]==0)B[a]=++nn;
        if(B[b]==0)B[b]=++nn;
        A[B[a]]=B[b];
    }
    int ans=n;
    for1(n)deg[A[i]]++;
    set<pii>C;
    for1(n){
        if(A[i]!=i && A[A[i]]==i){ans--;;vis[i]=1;}
        else C.insert({deg[i],i});
    }
    while(C.size()){
        int v=(*C.begin()).S;C.erase(C.begin());
        vis[v]=1;
        if(vis[A[v]]==0){
            ans--;
            vis[A[v]]=1;
            C.erase({deg[A[v]],A[v]});
            if(vis[A[A[v]]]==0){
                C.erase({deg[A[A[v]]],A[A[v]]});
                deg[A[A[v]]]--;
                C.insert({deg[A[A[v]]],A[A[v]]});
            }   
        }
    }
    cout<<ans<<endl;
    


}

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