Submission #870897

#	Time	Username	Problem	Language	Result	Execution time	Memory
870897		aykhn	Regions (IOI09_regions)	C++17	55 / 100	1827 ms	66164 KiB

regions

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

#define pb push_back
#define pii pair<int, int>
#define mpr make_pair
#define fi first
#define se second
#define all(v) v.begin(), v.end()

const int MXN = 2e5 + 5;
const int B = 2000;

int n, r, q;
int reg[MXN], p[MXN];
vector<int> idx[MXN];
vector<pii> v1[MXN];
vector<int> v2[MXN];
vector<int> adj[MXN];
int dp[MXN];
int in[MXN], out[MXN];
int tim = -1;
int cur = -1;
map<pii, ll> mp;

void dfs(int a, int p)
{
    in[a] = ++tim;
    for (int v : adj[a])
    {
        if (v == p) continue;
        dfs(v, a);
    }
    out[a] = ++tim;
}

void dfs1(int a, int p, int seen)
{
    if (reg[a] != cur) mp[mpr(cur, reg[a])] = mp[mpr(cur, reg[a])] + seen;
    for (int v : adj[a])
    {
        if (v == p) continue;
        dfs1(v, a, seen + (reg[a] == cur));
        dp[a] += dp[v];
    }
    dp[a] += (reg[a] == cur);
    if (cur != reg[a] && idx[reg[a]].size() < B) mp[mpr(reg[a], cur)] = mp[mpr(reg[a], cur)] + dp[a];
}

signed main()
{
    cin >> n >> r >> q;
    cin >> reg[1];
    idx[reg[1]].pb(1);
    for (int i = 2; i <= n; i++)
    {
        cin >> p[i] >> reg[i];
        adj[p[i]].pb(i);
        idx[reg[i]].pb(i);
    }
    dfs(1, 1);
    for (int i = 1; i <= r; i++)
    {
        for (int x : idx[i])
        {
            v1[i].pb(mpr(in[x], 1));
            v1[i].pb(mpr(out[x] + 1, -1));
            v2[i].pb(in[x]);
        }
        sort(all(v1[i]));
        sort(all(v2[i]));
    }
    for (int i = 1; i <= r; i++)
    {
        if (idx[i].size() < B) continue; 
        cur = i;
        dfs1(1, 1, 0);
    }
    while (q--)
    {
        int u, v;
        cin >> u >> v;
        if (mp.find(mpr(u, v)) != mp.end())
        {
            cout << mp[mpr(u, v)] << endl;
            continue;
        }
        int i = 0;
        int j = 0;
        ll ans = 0;
        int rn = 0;
        while (i < v1[u].size() && j < v2[v].size())
        {
            if (v1[u][i].fi <= v2[v][j]) rn += v1[u][i++].se;
            else 
            {
                ans = ans + rn;
                j++;
            }
        }
        mp[mpr(u, v)] = ans;
        cout << ans << endl;
    }
}

Compilation message (stderr)

regions.cpp: In function 'int main()':
regions.cpp:94:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   94 |         while (i < v1[u].size() && j < v2[v].size())
      |                ~~^~~~~~~~~~~~~~
regions.cpp:94:38: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   94 |         while (i < v1[u].size() && j < v2[v].size())
      |                                    ~~^~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 40 / 85