Submission #1248468

#	Time	Username	Problem	Language	Result	Execution time	Memory
1248468		chikien2009	Port Facility (JOI17_port_facility)	C++20	10 / 100	12 ms	23880 KiB

port_facility

#include <bits/stdc++.h>

using namespace std;

void setup()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

struct DSU
{
    int par[2000001], sz[2000001], col[2000001];
    inline int Get(int inp)
    {
        return (par[inp] == inp ? inp : Get(par[inp]));
    }
    inline int Col(int inp)
    {
        return (par[inp] == inp ? col[inp] : col[inp] ^ Col(par[inp]));
    }
    inline DSU()
    {
        for (int i = 0; i <= 2e6; ++i)
        {
            par[i] = i;
            sz[i] = 1;
            col[i] = 0;
        }
    }
    inline void Combine(int ina, int inb)
    {
        int ba = ina, bb = inb;
        ina = Get(ina);
        inb = Get(inb);
        if (ina != inb)
        {
            if (sz[ina] < sz[inb])
            {
                swap(ina, inb);
            }
            sz[ina] += sz[inb];
            par[inb] = ina;
            if (col[bb] == col[ba])
            {
                col[inb] = 1 ^ col[ina];
            }
        }
        else if (Col(ba) == Col(bb))
        {
            cout << 0;
            exit(0);
        }
    }
} dsu;

int n, a[2000001], res = 1;
const int mod = 1e9 + 7;
vector<list<int>> all;
list<int> temp;

int main()
{
    setup();

    cin >> n;
    for (int i = 0, j; i < n; ++i)
    {
        cin >> j >> a[j];
    }
    // list::splice() work very fast, read more on internet
    for (int i = 1; i <= 2 * n; ++i)
    {
        if (a[i] != 0)
        {
            all.push_back({{a[i]}});
        }
        else
        {
            temp.clear();
            while (true)
            {
                if (all.back().back() == i)
                {
                    all.back().pop_back();
                    if (all.back().empty())
                    {
                        all.pop_back();
                    }
                    break;
                }
                dsu.Combine(i, all.back().back());
                temp.splice(temp.begin(), all.back());
                all.pop_back();
            }
            if (!temp.empty())
            {
                all.push_back({});
                all.back().splice(all.back().begin(), temp);
            }
        }
    }
    for (int i = 1; i <= 2 * n; ++i)
    {
        if (a[i] != 0 && dsu.Get(a[i]) == a[i])
        {
            (res *= 2) %= mod;
        }
    }
    cout << res;
    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 12
• Subtask 3: 0 / 56
• Subtask 4: 0 / 22