Submission #448823

#	Time	Username	Problem	Language	Result	Execution time	Memory
448823		julian33	Love Polygon (BOI18_polygon)	C++14	0 / 100	176 ms	20132 KiB

polygon

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {
    cerr<<vars<<" = ";
    string delim="";
    (...,(cerr<<delim<<values,delim=", "));
    cerr<<"\n";
}
#else
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {}
#endif

#define pb push_back
#define sz(x) (int)(x.size())
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
template<typename T> inline void maxa(T& a,T b){a=max(a,b);}
template<typename T> inline void mina(T& a,T b){a=min(a,b);} 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int mxN=2e5+5; //make sure this is right
const int mod=1e9+7;

vector<string> all;
int get(string s){return lower_bound(all.begin(),all.end(),s)-all.begin()+1;}
int go[mxN],deg[mxN],p[mxN],colour[mxN],done[mxN],each[mxN][5],yes[mxN];
vector<int> component;

/*
red -> part of cycle
blue -> can be paired with non-red node
green -> points to red
yellow -> blue
pink -> part of 2 cycle
orange -> points to self

1 = red
2 = blue
3 = green
4 = yellow
5 = pink
6 = orange
*/

struct DSU{
    int uf[mxN];
    void init(){memset(uf,-1,sizeof(uf));}
    int find(int x){return uf[x]<0?x:uf[x]=find(uf[x]);}
    bool same(int x,int y){return find(x)==find(y);}
    void unite(int x,int y){
        x=find(x); y=find(y);
        if(x==y)
            return;
        if(uf[x]>uf[y])
            swap(x,y);
        uf[x]+=uf[y]; uf[y]=x;
    }   
};

void dfs(int at){
    component.pb(at);
    int nxt=go[at];
    done[at]=1;
    if(nxt==at){
        done[at]=2;
        colour[at]=6;
        return;
    }
    if(done[nxt]==1){
        colour[at]=1;
        colour[nxt]=7;
    } else if(done[nxt]==2){
        if(colour[nxt]==1)
            colour[at]=3;
        else
            colour[at]=4;
    } else{
        dfs(nxt);
        if(colour[nxt]==7){
            colour[at]=3;
            colour[nxt]=1;
        } else if(colour[nxt]==1 && colour[at]!=7){
            colour[at]=1;
        } else if(colour[nxt]!=1){
            colour[at]=4;
        }
    }
    done[at]=2;
}

void change_yellow(int at){
    if(colour[at]!=4)
        return;
    int nxt=go[at];
    if(colour[nxt]==1 || colour[nxt]==2 || colour[nxt]==5)
        return;
    colour[at]=colour[nxt]=2;
    change_yellow(go[nxt]);
}

DSU dsu;

int main(){
    cin.sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    #ifdef LOCAL
        freopen("input.txt","r",stdin);
        freopen("output.txt","w",stdout);
    #endif

    int n; cin>>n; dsu.init();
    if(n&1){
        cout<<-1<<"\n";
        return 0;
    }
    vector<pair<string,string>> off;
    for(int i=0;i<n;i++){
        string s,t; cin>>s>>t;
        all.pb(s); all.pb(t);
        off.pb({s,t});
    }
    sort(all.begin(),all.end());
    all.resize(unique(all.begin(),all.end())-all.begin());
    for(auto &i:off){
        int u=get(i.first);
        int v=get(i.second);
        go[u]=v;
        deg[v]++;
        deb(u,v);
        if(go[v]==u && u!=v){
            colour[v]=colour[u]=5;
            done[u]=done[v]=2;
        } else{
            dsu.unite(u,v);
        }
    }
    for(int i=1;i<=n;i++)
        p[i]=i;
    sort(p+1,p+1+n,[&](auto x,auto y){return deg[x]<deg[y];});
    int ans=0;
    for(int i=1;i<=n;i++){
        if(!done[p[i]]){
            component.clear();
            deb(p[i]);
            dfs(p[i]);
            if(colour[p[i]]==4)
                change_yellow(p[i]);
            int rep=dsu.find(p[i]);
            yes[rep]=1;
            for(int &j:component){
                deb(j,colour[j]);
                each[rep][0]+=colour[j]==1;
                each[rep][1]+=colour[j]==2;
                each[rep][2]+=colour[j]==3;
                each[rep][3]+=colour[j]==4;
                each[rep][4]+=colour[j]==6;
            }
        }
    }
    for(int i=1;i<=n;i++){
        if(!yes[i])
            continue;
        deb(each[i][0],each[i][1],each[i][2],each[i][3],each[i][4]);
        ans+=each[i][0]/2+each[i][1]/2+each[i][2]+each[i][3]+each[i][4];
        if(abs(dsu.uf[i])&1)
            ans++;
    }
    cout<<ans<<"\n";
}

• Subtask 1: 0 / 21
• Subtask 2: 0 / 25
• Subtask 3: 0 / 29
• Subtask 4: 0 / 25