Submission #1003093

#	Time	Username	Problem	Language	Result	Execution time	Memory
1003093		vjudge1	Subtree (INOI20_subtree)	C++17	12 / 100	560 ms	1048576 KiB

Main

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define endl "\n"
 
using namespace std;
using namespace __gnu_pbds;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<class T> using ordered_set = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
const ll N = 1e5 + 5, mod = 1e9 + 7;
vector<ll> g[N];
ll dp[N];
void dfs(ll v, ll par = 0)
{
    dp[v] = 1;
    for (ll to : g[v]) if (to != par) dfs(to, v), dp[v] = (dp[to] + 1) * dp[v] % mod;
}
void solve()
{
    ll n, m;
    cin >> n >> m;
    while (m--)
    {
        ll a, b;
        cin >> a >> b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    dfs(1);
    ll ans = 0;
    for (ll i = 1; i <= n; i++) ans = (ans + dp[i]) % mod;
    cout << ans << endl;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    ll t = 1;
    // precomp();
    // cin >> t;
    for (ll cs = 1; cs <= t; cs++)
        solve();
    // cerr << "\nTime elapsed: " << clock() * 1000.0 / CLOCKS_PER_SEC << " ms\n";
}

• Subtask 1: 0 / 8
• Subtask 2: 12 / 12
• Subtask 3: 0 / 30
• Subtask 4: 0 / 50