oj.uz

Submission #817118

# Submission time Handle Problem Language Result Execution time Memory
817118 2023-08-09T09:38:21 Z t6twotwo Parking (CEOI22_parking) C++17
18 / 100
 90 ms 15380 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){
        int a=x[i]/2;
        int b=y[i]/2;
        assert(a!=b);
        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]);
            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]);
        FOR(j,sz(T[i][1])) park(T[i][1][j]);
        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]);
            FOR(k,sz(T[i][j])) park(T[i][j][k]);
            park(S[i][j-1]);
        }
        park(S[i][0]);
        if(sz(S[i])%2){
            FOR(j,sz(T[i].bk)) park(T[i].bk[j]);
            park(S[i].bk);
        }
    }
    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 40 ms 5204 KB Output is correct
2 Correct 41 ms 5440 KB Output is correct
3 Correct 31 ms 4320 KB Output is correct
4 Correct 29 ms 4188 KB Output is correct
5 Correct 41 ms 5508 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 1 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 1 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 90 ms 15380 KB Output is partially correct
11 Correct 27 ms 3368 KB Output is correct
12 Correct 36 ms 4556 KB Output is correct
13 Partially correct 68 ms 8744 KB Output is partially correct
14 Correct 43 ms 8968 KB Output is correct
15 Correct 42 ms 8652 KB Output is correct
16 Partially correct 85 ms 14256 KB Output is partially correct
17 Correct 47 ms 6604 KB Output is correct
18 Partially correct 81 ms 11628 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 -