Submission #1212023

#	Time	Username	Problem	Language	Result	Execution time	Memory
1212023		enjeeeff	Regions (IOI09_regions)	C++20	Compilation error	0 ms	0 KiB

regions

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

#define ll long long
#define vec vector

const ll maxn = 2e5 + 1, maxreg = 25001;
const ll block = sqrt(maxn);
vec<ll> gr[maxn];

ll track[maxn], regionof[maxn], sizes[maxn], tin[maxn], tout[maxn];
unordered_map<ll, unordered_map<ll, ll>> precalc;

vec<ll> enterTimes[maxn];
vec<ll> setOfRegion[maxreg];

ll timer = 0;
void dfs(ll v, ll par, ll reg)
{
    precalc[reg][regionof[v]] += track[reg];
    track[regionof[v]]++;
    for (auto &e : gr[v])
        if (e != par)
            dfs(e, v, reg);
    track[regionof[v]]--;
}

void dfs1(ll v, ll par = -1)
{
    tin[v] = ++timer;
    enterTimes[regionof[v]].push_back(tin[v]);
    for (auto &e : gr[v])
        if (e != par)
            dfs1(e, v);
    track[regionof[v]]--;
    tout[v] = timer;
}

int main()
{
    ll n, r, q;
    cin >> n >> r >> q;
    
    ll i;
    ll reg, belongs;
    cin >> reg;
    sizes[reg]++;
    setOfRegion[reg].push_back(1);
    
    for (i = 2; i <= n; i++)
    {
        cin >> belongs >> reg;
        
        regionof[i] = reg;
        gr[belongs].push_back(i);
        setOfRegion[reg].push_back(i);
        sizes[reg]++;
    }
    
    dfs1(1);
    for (i = 1; i <= r; i++)
        if (sizes[i] >= block)
            dfs(1, -1, i);
    
    while (q--)
    {
        ll parent, child;
        cin >> parent >> child;
        
        if (sizes[parent] >= block)
            cout << precalc[parent][child] << endl;
        else
        {
            ll res = 0;
            for (auto &el : setOfRegion[parent])
                res += upper_bound(enterTimes[child].begin(), enterTimes[child].end(), tout[el]) - lower_bound(enterTimes[child].begin(), enterTimes[child].end(), tin[el]);
            
            cout << res << endl;
        }
    }
}

Compilation message (stderr)

regions.cpp:10:18: error: 'sqrt' was not declared in this scope
   10 | const ll block = sqrt(maxn);
      |                  ^~~~