Submission #934187

#	Time	Username	Problem	Language	Result	Execution time	Memory
934187		bobbilyking	Regions (IOI09_regions)	C++17	100 / 100	3478 ms	38024 KiB

regions

#pragma GCC target ("avx2")
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")

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

typedef int ll;
typedef long double ld;
typedef pair<ll, ll> pl;
typedef vector<ll> vl;
#define FD(i, r, l) for(ll i = r; i > (l); --i)

#define K first
#define V second
#define G(x) ll x; cin >> x;
#define GD(x) ld x; cin >> x;
#define GS(s) string s; cin >> s;
#define EX(x) { cout << x << '\n'; exit(0); }
#define A(a) (a).begin(), (a).end()
#define F(i, l, r) for (ll i = l; i < (r); ++i)

template<typename A, typename B>
A& chmax(A &a, B b) { return a < b ? (a=b): a; }

template<typename A, typename B>
A& chmin(A &a, B b) { return a > b ? (a=b): a; }




const ll NN = 2e5 + 1;
const ll HEAVYTH = 550;
// const ll HEAVYTH = 750;
const ll RR = 2.5e4 + 1;
const ll AMT = RR / HEAVYTH + 6;

ll label[NN], tin[NN], tout[NN];
vl people[RR];
vl adj[NN];

vl dfsorder;
vl heavies;


ll sz[NN];


void dfsinit(ll i) {
    static int time = 0;
    tin[i] = time++;
    dfsorder.push_back(i);
    sort(A(adj[i]), [&](ll a, ll b) {
        return sz[a] > sz[b];
    });
    for (auto x: adj[i]) dfsinit(x);
    tout[i] = time;
}


bool isPar(ll i, ll j) {
    return tin[i] <= tin[j] and tin[j] < tout[i];
}

ll heavyRoot[AMT][RR];

void solveHeavyRoot(ll ask, ll put) {
    // compute number of ask labels on path to root, add to ans 
    vl stk;
    ll cnt = 0;

    for (auto x: dfsorder) {
        while (stk.size() and !isPar(stk.back(), x)) {
            cnt -= label[stk.back()] == ask;
            stk.pop_back();
        }
        cnt += label[x] == ask;
        stk.push_back(x);

        heavyRoot[put][label[x]] += cnt;

    }
}

ll containsHeavy[AMT][RR];

void solveContainsHeavy(ll ask, ll put) {
    // compute number of ask in subtree, then add to answer 
    vl ans(dfsorder.size() + 1);
    FD(i, ll(dfsorder.size()) - 1, -1) {
        ll x = dfsorder[i];
        for (auto y: adj[x]) ans[x] += ans[y];
        ans[x] += label[x] == ask;
        
        containsHeavy[put][label[x]] += ans[x];
    }
}

vl peopleWhenQuerying[RR];

int main(){
    ios_base::sync_with_stdio(false); cin.tie(0);
    
    G(n) G(r) G(q)
    
    cin >> label[1]; people[label[1]].push_back(1);

    vl p(n+1);
    F(i, 2, n+1) {
        G(par) cin >> label[i]; 
        adj[par].push_back(i);
        people[label[i]].push_back(i);

        p[i] = par;
    }

    FD(i, n, 1) sz[p[i]]+= ++sz[i];

    dfsinit(1);

    F(i, 1, r+1) if (people[i].size() >= HEAVYTH) {
        heavies.push_back(i);
    }

    F(i, 0, heavies.size()) {
        solveHeavyRoot(heavies[i], i);
    }

    F(i, 0, heavies.size()) {
        solveContainsHeavy(heavies[i], i);
    }

    F(i, 1, r+1) if (people[i].size() < HEAVYTH) {
        peopleWhenQuerying[i] = people[i];
        for (auto &x: peopleWhenQuerying[i]) x = tin[x];
        sort(A(peopleWhenQuerying[i]));
    }

    // cout << heavies.size() << " vs " << r << endl;

    // exit(0);
    
    while (q--) {
        G(r1) G(r2)
        
        if (people[r1].size() >= HEAVYTH) {
            cout << heavyRoot[lower_bound(A(heavies), r1) - heavies.begin()][r2] << endl;
        } else if (people[r2].size() >= HEAVYTH) {
            cout << containsHeavy[lower_bound(A(heavies), r2) - heavies.begin()][r1] << endl;
        } else {
            ll ans = 0;
            for (auto x: people[r1]) {
                ans += lower_bound(A(peopleWhenQuerying[r2]), tout[x]) - lower_bound(A(peopleWhenQuerying[r2]), tin[x]);
            }
            cout << ans << endl;
        }
    }
}

Compilation message (stderr)

regions.cpp: In function 'int main()':
regions.cpp:22:37: warning: comparison of integer expressions of different signedness: 'll' {aka 'int'} and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 | #define F(i, l, r) for (ll i = l; i < (r); ++i)
      |                                     ^
regions.cpp:126:5: note: in expansion of macro 'F'
  126 |     F(i, 0, heavies.size()) {
      |     ^
regions.cpp:22:37: warning: comparison of integer expressions of different signedness: 'll' {aka 'int'} and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 | #define F(i, l, r) for (ll i = l; i < (r); ++i)
      |                                     ^
regions.cpp:130:5: note: in expansion of macro 'F'
  130 |     F(i, 0, heavies.size()) {
      |     ^

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