Submission #1277010

#	Time	Username	Problem	Language	Result	Execution time	Memory
1277010		tvgk	Usmjeri (COCI17_usmjeri)	C++20	140 / 140	295 ms	76640 KiB

usmjeri

#include<bits/stdc++.h>
using namespace std;
#define task "Direct"
#define ll long long
#define fi first
#define se second
#define ii pair<ll, ll>
const int mxN = 3e5 + 7, MOD = 1e9 + 7;

int n, par[mxN][25], h[mxN], q, cnt[mxN], ans;
ii dsu[mxN];
vector<int> w[mxN];

void Pre(int j)
{
    dsu[j] = {j, 0};
    for (int i = 1; i <= 20; i++)
        par[j][i] = par[par[j][i - 1]][i - 1];

    for (int i : w[j])
    {
        if (h[i])
            continue;

        h[i] = h[j] + 1;
        par[i][0] = j;
        Pre(i);
    }
}

int LCA(int u, int v)
{
    if (h[u] < h[v])
        swap(u, v);

    for (int i = 20; i >= 0; i--)
    {
        if (h[par[u][i]] >= h[v])
            u = par[u][i];
    }

    if (u == v)
        return u;

    for (int i = 20; i >= 0; i--)
    {
        if (par[u][i] != par[v][i])
        {
            u = par[u][i];
            v = par[v][i];
        }
    }
    return par[u][0];
}

int branch(int u, int v)
{
    for (int i = 20; i >= 0; i--)
    {
        if (h[par[u][i]] > h[v])
            u = par[u][i];
    }
    return u;
}

void Find(int j)
{
    if (dsu[j].fi != j)
    {
        Find(dsu[j].fi);
        int grp = dsu[j].fi;
        dsu[j].se ^= dsu[grp].se;
        dsu[j].fi = dsu[grp].fi;
    }
}

bool Union(int u, int v, int tt)
{
    Find(u);
    Find(v);
    int uu = dsu[u].fi;
    int vv = dsu[v].fi;

    if (uu == vv)
        return (dsu[u].se ^ dsu[v].se) == tt;

    dsu[vv].fi = uu;
    dsu[vv].se = dsu[v].se ^ tt ^ dsu[u].se;
    return 1;
}

void DFS(int j)
{
    for (int i : w[j])
    {
        if (i == par[j][0])
            continue;

        DFS(i);
        cnt[j] += cnt[i];
    }
    if (cnt[j])
        ans *= Union(j, par[j][0], 0);
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie();
    cout.tie();
//    freopen(task".INP", "r", stdin);
//    freopen(task".OUT", "w", stdout);

    cin >> n >> q;
    for (int i = 1; i < n; i++)
    {
        int u, v;
        cin >> u >> v;
        w[u].push_back(v);
        w[v].push_back(u);
    }
    h[1] = 1;
    Pre(1);

    ans = 1;
    for (int i = 1; i <= q; i++)
    {
        int u, v;
        cin >> u >> v;

        int root = LCA(u, v);
        cnt[u]++;
        cnt[v]++;

        u = branch(u, root);
        v = branch(v, root);
        cnt[u]--;
        cnt[v]--;

        if (u != root && v != root)
            ans *= Union(u, v, 1);
    }
    DFS(1);

    for (int i = 2; i <= n; i++)
    {
        Find(i);
        if (dsu[i].fi == i)
            ans = ans * 2 % MOD;
    }
    cout << ans;
}

• Subtask 1: 14 / 14
• Subtask 2: 14 / 14
• Subtask 3: 14 / 14
• Subtask 4: 14 / 14
• Subtask 5: 14 / 14
• Subtask 6: 14 / 14
• Subtask 7: 14 / 14
• Subtask 8: 14 / 14
• Subtask 9: 14 / 14
• Subtask 10: 14 / 14