Submission #996251

#	Time	Username	Problem	Language	Result	Execution time	Memory
996251		GrindMachine	Parking (CEOI22_parking)	C++17	0 / 100	2054 ms	524288 KiB

Main

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

void solve(int test_case)
{
    ll n,m; cin >> n >> m;
    vector<vector<ll>> a(m+5);
    rep1(i,m){
        rep1(j,2){
            ll x; cin >> x;
            if(x){
                a[i].pb(x);
            }
        }
    }

    vector<pll> ans;

    while(true){
        bool ok = true;
        rep1(i,m){
            if(sz(a[i]) == 1){
                ok = false;
            }
            else if(sz(a[i]) == 2){
                if(a[i][0] != a[i][1]){
                    ok = false;
                }
            }
        }

        if(ok) break;

        vector<ll> pending(n+5,-1);
        rep1(i,m){
            if(sz(a[i]) == 1){
                pending[a[i][0]] = i;
            }
        }

        bool done = false;

        rep1(i,m){
            if(sz(a[i]) == 2 and a[i][0] == a[i][1]) conts;
            if(sz(a[i]) == 2){
                if(pending[a[i][1]] != -1){
                    ll x = a[i][1];
                    a[i].pop_back();
                    a[pending[x]].pb(x);
                    ans.pb({i,pending[x]});
                    done = true;
                    break;
                }
            }
            if(sz(a[i]) == 1){
                ll x = a[i][0];
                if(pending[x] != -1 and pending[x] != i){
                    a[i].pop_back();
                    a[pending[x]].pb(x);
                    ans.pb({i,pending[x]});
                    done = true;
                    break;                    
                }
            }
        }

        if(done) conts;

        ll free_pos = -1;
        rep1(i,m){
            if(sz(a[i]) == 0) free_pos = i;
        }

        if(free_pos == -1){
            cout << -1 << endl;
            return;
        }

        rep1(i,m){
            if(sz(a[i]) == 2){
                ll x = a[i][1];
                a[i].pop_back();
                a[free_pos].pb(x);
                ans.pb({i,free_pos});
                break;
            }
        }
    }

    cout << sz(ans) << endl;
    for(auto [x,y] : ans){
        cout << x << " " << y << endl;
    }
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 25
• Subtask 4: 0 / 15
• Subtask 5: 0 / 25
• Subtask 6: 0 / 15