Submission #591266

#	Time	Username	Problem	Language	Result	Execution time	Memory
591266		Loki_Nguyen	Usmjeri (COCI17_usmjeri)	C++14	140 / 140	381 ms	77588 KiB

usmjeri

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<ll, int>
#define pii pair<int, int>
#define fi first
#define se second
#define pb push_back

const int N = 3e5 + 3;
const int M = 1 << 24;
const int mod = 1e9 + 7;
const int base = 300;
const ll inf = 1e12;
int pw(int k, int n)
{
    int total = 1;
    for (; n; n >>= 1)
    {
        if (n & 1)
            total = total * k % mod;
        k = k * k % mod;
    }
    return total;
}
int m, n, t, k, a[N], ans, b[N * 2], c[N], d[N], lab[N * 2], tong, h[N], P[N][20];
vector<int> adj[N];
void dfs(int u, int p = 0)
{
    for (int v : adj[u])
    {
        if (v == p)
            continue;
        h[v] = h[u] + 1;
        P[v][0] = u;
        for (int i = 1; i <= 18; i++)
            P[v][i] = P[P[v][i - 1]][i - 1];
        dfs(v, u);
    }
}
int lca(int u, int v)
{
    if (h[u] < h[v])
        swap(u, v);
    int log = log2(h[u]);
    for (int i = log; i >= 0; i--)
    {
        if (h[u] >= h[v] + (1 << i))
            u = P[u][i];
    }
    if (u == v)
        return u;
    for (int i = log; i >= 0; i--)
    {
        if (P[u][i] && P[u][i] != P[v][i])
        {
            u = P[u][i];
            v = P[v][i];
        }
    }
    return P[v][0];
}
int fpar(int u, int dis)
{
    for (int i = 18; i >= 0; i--)
        if (dis >> i & 1)
            u = P[u][i];
    return u;
}
int findp(int u)
{
    return lab[u] < 0 ? u : lab[u] = findp(lab[u]);
}
void hop(int u, int v)
{
    u = findp(u);
    v = findp(v);
    if (u == v)
        return;
    if (lab[u] > lab[v])
        swap(u, v);
    lab[u] += lab[v];
    lab[v] = u;
}
void cal(int u, int p = 0)
{
    for (int v : adj[u])
    {
        if (v == p)
            continue;
        cal(v, u);
        d[u] += d[v];
    }
    if (d[u] && p)
    {
        hop(u, p);
        hop(u + n, p + n);
    }
}
void sol()
{
    cin >> n >> m;
    fill_n(lab, n * 2 + 1, -1);
    for (int i = 1; i < n; i++)
    {
        int x, y;
        cin >> x >> y;
        adj[x].pb(y);
        adj[y].pb(x);
    }
    dfs(1);
    for (int i = 1; i <= m; i++)
    {
        int x, y, z, lx = 0, ly = 0;
        cin >> x >> y;
        z = lca(x, y);
        if (z != x)
        {
            lx = fpar(x, h[x] - h[z] - 1);
            ++d[x];
            --d[lx];
        }
        if (z != y)
        {
            ly = fpar(y, h[y] - h[z] - 1);
            ++d[y];
            --d[ly];
        }
        if (lx && ly)
        {
            hop(lx, ly + n);
            hop(ly, lx + n);
        }
        //cout << z << " " << lx << " " << ly << '\n';
    }
    cal(1);
    ans = 1;
    for (int i = 2; i <= n; i++)
    {
        if (findp(i) == findp(i + n))
        {
            cout << 0;
            return;
        }
        if (!b[findp(i)])
        {
            b[findp(i)] = 1;
            ans = ans * 2 % mod;
        }
        if (!b[findp(i + n)])
        {
            b[findp(i + n)] = 1;
            // ans = ans * 2 % mod;
        }
    }
    cout << ans;
}
int main()
{
    cin.tie(0);
    cout.tie(0);
    ios_base::sync_with_stdio(0);
#define task "tests"
    if (fopen(task ".inp", "r"))
    {
        freopen(task ".inp", "r", stdin);
        freopen(task ".out", "w", stdout);
    }
    int ntest = 1;
    // cin >> ntest;
    while (ntest-- > 0)
        sol();
}
/*
10 10
259008492 685257993 684081919 849336162 185724174 230558609 147159919 225162936 734023603 130213023
2 1 4
2 4 7
2 2 8
2 4 10
2 5 8
2 5 6
2 1 10
2 3 8
2 1 8
2 2 4
2 1 6
*/

Compilation message (stderr)

usmjeri.cpp: In function 'int main()':
usmjeri.cpp:166:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  166 |         freopen(task ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
usmjeri.cpp:167:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  167 |         freopen(task ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• 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