oj.uz

Submission #817165

# Submission time Handle Problem Language Result Execution time Memory
817165 2023-08-09T10:01:56 Z t6twotwo Parking (CEOI22_parking) C++17
18 / 100
 96 ms 15420 KB 
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define FFOR(i,a,b,c) for(int i=(a);(c)>0?i<=(b):i>=(b);i+=(c))
#define FOOR(i,a,b) FFOR(i,a,(b)-1,1)
#define ROOF(i,a,b) FFOR(i,(b)-1,a,-1)
#define FOR(i,n) FOOR(i,0,n)
#define ROF(i,n) ROOF(i,0,n)
#define FORR(x,v) for(auto &x:v)
#define vc vector
#define sz(v) (int)((v).size())
#define bg begin()
#define en end()
#define em empty()
#define lb lower_bound
#define ub upper_bound
#define pb push_back
#define ppb pop_back()
#define eb emplace_back
#define bk back()
#define fr front()
#define pp pop()
#define all(v) (v).begin(),(v).end()
#define lla(v) (v).rbegin(),(v).rend()
#define f first
#define s second
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N,M;
    cin>>N>>M;
    vc<int> bot(M),top(M),x(N,-1),y(N),free;
    FOR(i,M){
        cin>>bot[i]>>top[i];
        bot[i]--,top[i]--;
        if(bot[i]!=-1) (x[bot[i]]==-1?x[bot[i]]:y[bot[i]])=i*2;
        if(top[i]!=-1) (x[top[i]]==-1?x[top[i]]:y[top[i]])=i*2+1;
        if(bot[i]==-1&&top[i]==-1) free.pb(i);
    }
    vc<pair<int,int>> ans;
    auto move=[&](int u,int v) {
        ans.eb(u,v);
        int a;
        if(top[u]!=-1){
            a=top[u];
            top[u]=-1;
        }else{
            a=bot[u];
            bot[u]=-1;
        }
        if(bot[v]==-1){
            (x[a]/2==u?x[a]:y[a])=v*2;
            bot[v]=a;
        }else{
            (x[a]/2==u?x[a]:y[a])=v*2+1;
            top[v]=a;
        }
        if(bot[u]==-1){
            free.pb(u);
        }
    };
    auto park=[&](int i,bool f){
        int a=x[i]/2;
        int b=y[i]/2;
        if(f) assert(top[a]==-1||top[b]==-1);
        if(top[b]!=-1) swap(a,b);
        move(a,b);
    };
    auto check=[&](){
        if(free.em){
            cout<<-1;
            exit(0);
        }
    };
    if(2*N<=M){
        auto good=[&](int a) {
            return (x[a]%2==1||top[x[a]/2]==-1)&&(y[a]%2==1||top[y[a]/2]==-1);
        };
        vc<bool> parked(N);
        FOR(i,N){
            if(x[i]%2==1&&y[i]%2==1){
                move(x[i]/2,free.bk);
                move(y[i]/2,free.bk);
                free.ppb;
            }
            if(x[i]/2==y[i]/2) parked[i]=1;
        }
        queue<int> q;
        FOR(i,N){
            if(!parked[i]&&good(i)){
                parked[i]=1;
                q.push(i);
            }
        }
        while(!q.em){
            int i=q.fr;q.pp;
            int a=x[i]/2;
            int b=y[i]/2;
            if(top[b]!=-1) swap(a,b);
            move(a,b);
            if(bot[a]!=-1){
                if(!parked[bot[a]]&&good(bot[a])){
                    parked[bot[a]]=1;
                    q.push(bot[a]);
                }
            }
        }
        FOR(i,N){
            if(!parked[i]){
                cout<<-1;
                return 0;
            }
        }
        cout<<sz(ans)<<"\n";
        for(auto[x,y]:ans){
            cout<<x+1<<" "<<y+1<<"\n";
        }
        return 0;
    }
    vc<bool> vis(M);
    vc<vc<int>> S;
    vc<vc<vc<int>>> T;
    FOR(i,M){
        if(vis[i]||bot[i]==top[i])continue;
        int j=i,k=bot[i],f=0;
        S.pb({k});
        T.pb({});
        while(1){
            T.bk.pb({});
            vis[j]=1;
            k=f?bot[j]:top[j];
            while(k!=bot[i]&&x[k]%2!=y[k]%2){
                T.bk.bk.pb(k);
                j^=(x[k]/2)^(y[k]/2);
                vis[j]=1;
                k=f?bot[j]:top[j];
            }
            if (k==bot[i])break;
            S.bk.pb(k);
            j^=(x[k]/2)^(y[k]/2);
            f^=1;
        }
    }
    FOR(i,sz(S)){
        if (sz(S[i])==1){
            check(); int t=free.bk; free.ppb;
            int a=x[S[i][0]];
            int b=y[S[i][0]];
            if (a%2==0) swap(a,b);
            move(a/2,t);
            ROF(j,sz(T[i][0])) park(T[i][0][j],0);
            move(b/2,t);
            continue;
        }
        check(); int t=free.bk; free.ppb;
        move(x[S[i][1]]/2,t);
        move(y[S[i][1]]/2,t);
        ROF(j,sz(T[i][0])) park(T[i][0][j],0);
        FOR(j,sz(T[i][1])) park(T[i][1][j],0);
        FFOR(j,3,sz(S[i])-1,2){
            check(); int t=free.bk;free.ppb;
            move(x[S[i][j]]/2,t);
            move(y[S[i][j]]/2,t);
            ROF(k,sz(T[i][j-1])) park(T[i][j-1][k],0);
            FOR(k,sz(T[i][j])) park(T[i][j][k],0);
            park(S[i][j-1],1);
        }
        park(S[i][0],1);
        if(sz(S[i])%2){
            FOR(j,sz(T[i].bk)) park(T[i].bk[j],0);
            park(S[i].bk,1);
        }
    }
    cout<<sz(ans)<<"\n";
    for(auto[x,y]:ans){
        cout<<x+1<<" "<<y+1<<"\n";
    }
    return 6/22;
}

Subtask #1
0.0 / 10.0

# Verdict Execution time Memory Grader output
1 Incorrect 0 ms 212 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 36 ms 5304 KB Output is correct
2 Correct 46 ms 5444 KB Output is correct
3 Correct 35 ms 4404 KB Output is correct
4 Correct 29 ms 4216 KB Output is correct
5 Correct 42 ms 5436 KB Output is correct

Subtask #3
5.0 / 25.0

# Verdict Execution time Memory Grader output
1 Partially correct 1 ms 340 KB Output is partially correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Partially correct 1 ms 340 KB Output is partially correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Partially correct 1 ms 340 KB Output is partially correct
8 Correct 0 ms 340 KB Output is correct
9 Partially correct 1 ms 340 KB Output is partially correct

Subtask #4
3.0 / 15.0

# Verdict Execution time Memory Grader output
1 Partially correct 1 ms 340 KB Output is partially correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Partially correct 1 ms 340 KB Output is partially correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Partially correct 1 ms 340 KB Output is partially correct
8 Correct 0 ms 340 KB Output is correct
9 Partially correct 1 ms 340 KB Output is partially correct
10 Partially correct 85 ms 15420 KB Output is partially correct
11 Correct 29 ms 3412 KB Output is correct
12 Correct 46 ms 4512 KB Output is correct
13 Partially correct 68 ms 8740 KB Output is partially correct
14 Correct 45 ms 8944 KB Output is correct
15 Correct 44 ms 8708 KB Output is correct
16 Partially correct 81 ms 14240 KB Output is partially correct
17 Correct 40 ms 6624 KB Output is correct
18 Partially correct 96 ms 11616 KB Output is partially correct

Subtask #5
0.0 / 25.0

# Verdict Execution time Memory Grader output
1 Runtime error 1 ms 724 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #6
0.0 / 15.0

# Verdict Execution time Memory Grader output
1 Incorrect 0 ms 212 KB Output isn't correct
2 Halted 0 ms 0 KB -