Submission #491625

#	Time	Username	Problem	Language	Result	Execution time	Memory
491625		blue	Logičari (COCI21_logicari)	C++17	110 / 110	93 ms	26588 KiB

Main

#include <iostream>
#include <vector>
#include <queue>
using namespace std;

const long long max_n = 100'000;

long long n;

const long long INF = 1'000'000;

long long dp[1+max_n][4];
vector<long long> children[1+max_n];
vector<long long> edge[1+max_n];
vector<long long> degree(1+max_n, 0);

void compute(long long u)
{
    // cerr << "compute " << u << '\n';
    vector<long long> sm(4, 0);
    long long min13 = INF;
    long long min02 = INF;
    for(long long v: children[u])
    {
        for(long long k = 0; k < 4; k++)
        {
            sm[k] += dp[v][k];
        }
        min13 = min(min13, dp[v][1] - dp[v][3]);
        min02 = min(min02, dp[v][0] - dp[v][2]);
    }
    // cerr << sm[0] << ' ' << sm[1] << ' ' << sm[2] << ' ' << sm[3] << ' ' << min13 << ' ' << min02 << '\n';
    dp[u][0] = 1 + sm[3] + min13;
    dp[u][1] = 1 + sm[3];
    dp[u][2] = sm[2] + min02;
    dp[u][3] = sm[2];

    for(long long k = 0; k < 4; k++) if(dp[u][k] >= INF) dp[u][k] = INF;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> n;

    for(long long e = 1; e <= n; e++)
    {
        long long a, b;
        cin >> a >> b;

        edge[a].push_back(b);
        edge[b].push_back(a);

        degree[a]++;
        degree[b]++;
    }

    queue<long long> tbv;
    for(long long i = 1; i <= n; i++)
    {
        if(degree[i] == 1) tbv.push(i);
    }

    vector<bool> visit(1+n, 0);

    while(!tbv.empty())
    {
        long long u = tbv.front();
            // cerr << "bfs " << u << '\n';
        tbv.pop();
        visit[u] = 1;

        for(long long v: edge[u])
        {
            if(degree[v] == 1) continue;

            children[v].push_back(u);
            degree[v]--;
            if(degree[v] == 1)
                tbv.push(v);
        }

        compute(u);
    }


    long long s = 1;
    while(visit[s]) s++;

    vector<long long> chain;

    // cerr << "s = " << s << '\n';

    // cerr << "check\n";

    while(1)
    {
        chain.push_back(s);
        visit[s] = 1;

        long long nv = -1;
        for(long long v: edge[s])
        {
            if(visit[v]) continue;
            nv = v;
            break;
        }

        compute(s);

        // cerr << s << ' ' << nv << '\n';

        if(nv == -1) break;
        s = nv;

    }

    // for(long long i = 1; i <= n; i++)
    // {
    //     cerr << i << ": ";
    //     for(long long j = 0; j < 4; j++) cerr << dp[i][j] << ' ';
    //     cerr << '\n';
    // }

    // for(long long c: chain) cerr << c << ' ';
    // cerr << '\n';

    long long q = (long long)chain.size();

    //current index, current state, state -1
    long long dp2[q][4][4];

    /*
    0 = satisfied blue
    1 = unsatisfied blue
    2 = satisfied red
    3 = unsatisfied red
    */
    for(long long x = 0; x < 4; x++)
        for(long long y = 0; y < 4; y++)
            dp2[0][x][y] = INF;

    dp2[0][0][3] = dp[chain[0]][0];
    dp2[0][0][1] = dp[chain[0]][1];

    dp2[0][1][3] = dp[chain[0]][1];

    dp2[0][2][2] = dp[chain[0]][2];
    dp2[0][2][0] = dp[chain[0]][3];

    dp2[0][3][2] = dp[chain[0]][3];

    for(long long i = 1; i < q; i++)
    {
        for(long long y = 0; y < 4; y++)
        {
            dp2[i][0][y] = min(dp[chain[i]][0] + dp2[i-1][3][y], dp[chain[i]][1] + dp2[i-1][1][y]);
            dp2[i][1][y] = dp[chain[i]][1] + dp2[i-1][3][y];
            dp2[i][2][y] = min(dp[chain[i]][2] + dp2[i-1][2][y], dp[chain[i]][3] + dp2[i-1][0][y]);
            dp2[i][3][y] = dp[chain[i]][3] + dp2[i-1][2][y];
        }
    }

    long long ans = INF;
    for(long long x = 0; x < 4; x++)
        ans = min(ans, dp2[q-1][x][x]);

    if(ans == INF) ans = -1;

    cout << ans << '\n';
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 40 / 40
• Subtask 4: 50 / 50