Submission #1312659

#	Time	Username	Problem	Language	Result	Execution time	Memory
1312659		4QT0R	Sumtree (INOI20_sumtree)	C++20	10 / 100	295 ms	60860 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define ll long long

const ll mod = 1e9 + 7;

vector<ll> graph[200003];
ll fat[200003];
ll label[200003];
ll dep[200003];
ll id[200003];
ll seg_id[200003];
ll prep_siz[200003];
vector<ll> whole_path[200003];
vector<set<pair<ll, ll>>> tagged_on_path(1);
ll iter, seg_iter;

const ll base = 1 << 18;
ll tree[2 * base];

void add(ll a, ll b, ll x)
{
    a += base - 1;
    b += base + 1;
    while (a / 2 != b / 2)
    {
        if (!(a & 1))
            tree[a + 1] += x;
        if (b & 1)
            tree[b - 1] += x;
        a >>= 1;
        b >>= 1;
    }
}

ll query(ll v)
{
    v += base;
    ll ans = 0;
    while (v)
    {
        ans += tree[v];
        v >>= 1;
    }
    return ans;
}

void path_add(ll v, ll x)
{
    if (v == 0)
        return;
    add(seg_id[whole_path[id[v]][0]], seg_id[v], x);
    path_add(fat[whole_path[id[v]][0]], x);
}

void path_add(ll v, ll p, ll x)
{
    path_add(v, x);
    path_add(fat[p], -x);
}

ll val(ll v)
{
    return query(seg_id[v]);
}

void prep(ll v, ll p)
{
    fat[v] = p;
    prep_siz[v] = 1;
    for (auto u : graph[v])
    {
        if (u == p)
            continue;
        dep[u] = dep[v] + 1;
        prep(u, v);
        prep_siz[v] += prep_siz[u];
    }
    sort(graph[v].begin(), graph[v].end(), [&](ll v, ll u)
         { return prep_siz[v] > prep_siz[u]; });
}
void dfs(ll v, ll p, ll ind)
{
    id[v] = ind;
    seg_id[v] = ++seg_iter;
    tree[seg_iter + base] = prep_siz[v];
    whole_path[ind].push_back(v);
    for (auto u : graph[v])
    {
        if (u == p)
            continue;
        if (2 * prep_siz[u] > prep_siz[v])
            dfs(u, v, ind);
        else
        {
            tagged_on_path.push_back({});
            dfs(u, v, ++iter);
        }
    }
}

ll fact[500003];
ll fact_inv[500003];

ll fast_pow(ll a, ll b)
{
    if (b == 1)
        return a;
    ll cur = fast_pow(a, b / 2);
    cur = (cur * cur) % mod;
    if (b & 1)
        cur = (cur * a) % mod;
    return cur;
}

void init(ll &n, ll &r, ll &q)
{
    cin >> n >> r;
    for (ll i = 1, a, b; i < n; i++)
    {
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    cin >> q;

    fact[0] = 1;
    for (ll i = 1; i <= 500002; i++)
        fact[i] = (i * fact[i - 1]) % mod;
    fact_inv[500002] = fast_pow(fact[500002], mod - 2);
    for (ll i = 500001; i >= 0; i--)
        fact_inv[i] = ((i + 1) * fact_inv[i + 1]) % mod;
}

ll res(ll siz, ll tag)
{
    ll wyn = fact[siz + tag - 1];
    wyn = (wyn * fact_inv[tag]) % mod;
    wyn = (wyn * fact_inv[siz - 1]) % mod;
    return wyn;
}

ll ans, neg_vert;

ll Find(ll v)
{
    // cout << "\nLooking at " << v << " and I see: ";
    // for (auto [x, y] : tagged_on_path[id[v]])
    //     cout << x << ' ' << y << " | ";
    // cout << '\n';
    if (tagged_on_path[id[v]].empty() || ((*tagged_on_path[id[v]].begin()).first > dep[v]))
        return Find(fat[whole_path[id[v]][0]]);
    return prev(tagged_on_path[id[v]].lower_bound({dep[v] + 1, 0}))->second;
}

void print(ll n)
{
    for (ll i = 1; i <= n; i++)
    {
        cout << i << ' ' << Find(i) << ' ' << val(i) << '\n';
    }
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    ll n, q;
    init(n, label[1], q);
    prep(1, 0);
    dfs(1, 0, 0);
    ans = res(n, label[1]);
    cout << ans << '\n';
    tagged_on_path[id[1]].insert({dep[1], 1});
    for (ll i = 1, t, v, tag; i <= q; i++)
    {
        cin >> t >> v;
        if (t == 1)
            cin >> tag;

        ll up = Find(fat[v]), val_of_v = val(v), val_of_up = val(up);
        if (val_of_up < 0)
            neg_vert--;
        else
            ans = (ans * fast_pow(res(val_of_up, label[up]), mod - 2)) % mod;
        if (t == 1)
        {
            label[v] = tag;
            ans = (ans * res(val_of_v, label[v])) % mod;
            tagged_on_path[id[v]].insert({dep[v], v});
            path_add(fat[v], up, -val_of_v);
            val_of_up -= val_of_v;
        }
        else
        {
            val_of_up += val_of_v;
            path_add(fat[v], up, val_of_v);
            tagged_on_path[id[v]].erase({dep[v], v});
            ans = (ans * fast_pow(res(val_of_v, label[v]), mod - 2)) % mod;
            label[v] = 0;
        }
        if (val_of_up < 0)
            neg_vert++;
        else
            ans = (ans * res(val_of_up, label[up])) % mod;

        if (neg_vert)
            cout << "0\n";
        else
            cout << ans << '\n';
    }
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30