Submission #413440

#	Time	Username	Problem	Language	Result	Execution time	Memory
413440		JerryLiu06	Regions (IOI09_regions)	C++17	0 / 100	3324 ms	31984 KiB

regions

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using db = long double;
using str = string;

using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;

using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;

#define mp make_pair
#define f first
#define s second

#define sz(x) (int)(x).size()
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define sor(x) sort(all(x))
#define ft front()
#define bk back()
#define pb push_back
#define pf push_front

#define lb lower_bound
#define ub upper_bound

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define R0F(i, a) ROF(i, 0, a)
#define EACH(a, x) for (auto& a : x)

const int MOD = 1e9 + 7;
const int MXN = 2e5 + 10;
const int MXR = 25010;
const ll INF = 1e18;

const int BLOCK = 450;

int N, R, Q; vi adj[MXN]; int L[MXN]; // L[i] = Region of i

int timer = 1, in[MXN], out[MXN]; 

vi S1[MXR]; // Sorted list that divide into intervals
vi S2[MXR]; // Sorted list of all

int active[MXR];

vi large; int up[BLOCK][MXR], down[BLOCK][MXR];

int ind[MXR];

// Preorder Traversal ~ O(N)

void DFS(int X, int P) {
    in[X] = timer++; active[L[X]]++; S2[L[X]].pb(X);
    
    EACH(Y, adj[X]) if (Y != P) DFS(Y, X);

    out[X] = timer - 1; active[L[X]]--; 
    
    if (!active[L[X]]) S1[L[X]].pb(X);
}

// Get the answer when queried (A, B) ~ O(N)

int genAns(int A, int B) {
    int ans = 0; int L = 0, R = 0; int last = 0;

    while (L < sz(S1[A]) || R < sz(S2[B])) {
        if (L < sz(S1[A]) && (R >= sz(S2[B]) || in[S1[A][L]] < in[S2[B][R]])) last = out[S1[A][L++]];
        
        else { if (out[S2[B][R]] <= last) ans++; R++; }
    }
    return ans;
}

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

    cin >> N >> R >> Q >> L[1];

    FOR(i, 2, N + 1) { int A; cin >> A >> L[i]; adj[A].pb(i), adj[i].pb(A); }

    DFS(1, 0); 

    int cur = 0; FOR(i, 1, R + 1) if (sz(S2[i]) >= BLOCK) large.pb(i), ind[i] = cur++;

    F0R(i, sz(large)) {
        FOR(j, 1, R + 1) { 
            up[i][j] = genAns(large[i], j); 
            down[i][j] = genAns(j, large[i]); 
        }
    }
    F0R(i, Q) {
        int A, B; cin >> A >> B;
        
        if (sz(S2[A]) >= BLOCK) cout << up[ind[L[A]]][B] << "\n";
        
        else if (sz(S2[B]) >= BLOCK) cout << down[ind[L[A]]][B] << "\n";
        
        else cout << genAns(A, B) << "\n";
    }
}

• Subtask 1: 0 / 15
• Subtask 2: 0 / 85