Submission #638612

#	Time	Username	Problem	Language	Result	Execution time	Memory
638612		BhavayGoyal	Regions (IOI09_regions)	C++14	100 / 100	4380 ms	44652 KiB

regions

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

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<class T> using oset = 
            tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define ll long long
#define ld long double
#define ar array
#define vi vector<int>
#define vii vector<vector<int>>
#define pii pair<int, int>
#define pb push_back
#define all(x) x.begin(), x.end()
#define f first
#define s second
#define endl "\n"

const int MOD = 1e9+7;
const int inf = 1e9;
const ll linf = 1e18;

const int d4i[4]={-1, 0, 1, 0}, d4j[4]={0, 1, 0, -1};
const int d8i[8]={-1, -1, 0, 1, 1, 1, 0, -1}, d8j[8]={0, 1, 1, 1, 0, -1, -1, -1};


// -------------------------------------------------- Main Code --------------------------------------------------

const int N = 2e5+5;
vi g[N], members[N], arr[N];
int region[N], tin[N], tout[N], tarr[N], timer = 1;

void dfs(int src, int par) {
    tarr[timer] = region[src];
    tin[src] = timer++;
    for (auto ch : g[src]) if (ch != par) dfs(ch, src);
    tout[src] = timer-1;
}

vi largeregions;
vii preProcessing;

void dfs2(int src, int par, int i, int ct = 0) {
    for (auto ch : g[src]) {
        if (ch == par) continue;
        preProcessing[i][region[ch]] += ct;
        dfs2(ch, src, i, ct+(largeregions[i]==region[ch]));
    }
}

void sol() {
    int n, r, q; cin >> n >> r >> q;
    int sqn = sqrt(n)+1;
    for (int i = 1; i <= n; i++) {
        if (i == 1) cin >> region[i];
        else {
            int x; cin >> x >> region[i];
            g[i].pb(x);
            g[x].pb(i);
        }
        members[region[i]].pb(i);
    }

    dfs(1, -1);

    for (int i = 1; i <= r; i++) if (members[i].size() >= sqn) largeregions.pb(i);
    preProcessing = vii(largeregions.size(), vi(r+1, 0));
    for (int i = 0; i < largeregions.size(); i++) dfs2(1, -1, i, (largeregions[i]==region[1]));

    for (int i = 1; i <= n; i++) arr[tarr[i]].pb(i);

    while (q--) {
        int a, b; cin >> a >> b;
        int idx = lower_bound(all(largeregions), a) - largeregions.begin();
        if (idx < largeregions.size() && largeregions[idx] == a) {
            cout << preProcessing[idx][b] << endl;
            continue;
        }

        int ans = 0;
        for (auto ch : members[a]) {
            ans += (upper_bound(all(arr[b]), tout[ch]) - lower_bound(all(arr[b]), tin[ch]));
        }
        cout << ans << endl;
    }
}

int main () {
    // ios_base::sync_with_stdio(false);
    // cin.tie(NULL);
    int t = 1;
    // cin >> t; 
    while (t--) {
        sol();
    }
    return 0;
}

Compilation message (stderr)

regions.cpp: In function 'void sol()':
regions.cpp:70:56: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   70 |     for (int i = 1; i <= r; i++) if (members[i].size() >= sqn) largeregions.pb(i);
      |                                      ~~~~~~~~~~~~~~~~~~^~~~~~
regions.cpp:72:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   72 |     for (int i = 0; i < largeregions.size(); i++) dfs2(1, -1, i, (largeregions[i]==region[1]));
      |                     ~~^~~~~~~~~~~~~~~~~~~~~
regions.cpp:79:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |         if (idx < largeregions.size() && largeregions[idx] == a) {
      |             ~~~~^~~~~~~~~~~~~~~~~~~~~

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