Submission #696891

#	Time	Username	Problem	Language	Result	Execution time	Memory
696891		cig32	Diversity (CEOI21_diversity)	C++14	100 / 100	6293 ms	14580 KiB

diversity

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int MAXN = 3e5 + 10;
const int MOD = 1e9 + 7;
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
  int u = uniform_int_distribution<int>(x, y)(rng); return u;
}
int bm(int b, int p) {
  if(p==0) return 1 % MOD;
  int r = bm(b, p >> 1);
  if(p&1) return (((r*r) % MOD) * b) % MOD;
  return (r*r) % MOD;
}
int inv(int b) { 
  return bm(b, MOD-2);
}
int fastlog(int x) {
  return (x == 0 ? -1 : 64 - __builtin_clzll(x) - 1);
}
void printcase(int i) { cout << "Case #" << i << ": "; }

int freq[MAXN], ff[MAXN], n;

int block;
bool modui(pair<pair<int,int>,int> a, pair<pair<int,int>,int> b) {
  if(a.first.first / block != b.first.first / block) return a.first.first / block < b.first.first / block;
  return a.first.second < b.first.second;
}

bool byfreq(int x, int y) {
  return freq[x] < freq[y];
}
void solve(int tc) {
  int q;
  cin >> n >> q;
  int c = 300000;
  block = 1342;
  int arr[n+1];
  for(int i=1; i<=n; i++) {
    cin >> arr[i];
  }
  pair<pair<int,int>,int> qry[q+1];
  for(int i=1; i<=q; i++) {
    cin >> qry[i].first.first >> qry[i].first.second;
    qry[i].second = i;
  }
  sort(qry+1, qry+q+1, modui);
  int res[q+1];
  int l = qry[1].first.first, r = qry[1].first.first - 1;
  vector<int> v;
  // O(sqrt(n)) frequencies
  set<int> all; // set of all frequencies
  for(int i=1; i<=q; i++) {
    vector<int> tmp;
    while(l > qry[i].first.first) {
      l--;
      ff[freq[arr[l]]]--;
      if(ff[freq[arr[l]]] == 0) tmp.push_back(freq[arr[l]]);
      freq[arr[l]]++;
      ff[freq[arr[l]]]++;
      if(ff[freq[arr[l]]] == 1) tmp.push_back(freq[arr[l]]);
    }
    while(r > qry[i].first.second) {
      ff[freq[arr[r]]]--;
      if(ff[freq[arr[r]]] == 0) tmp.push_back(freq[arr[r]]);
      freq[arr[r]]--;
      ff[freq[arr[r]]]++;
      if(ff[freq[arr[r]]] == 1) tmp.push_back(freq[arr[r]]);
      r--;
    }
    while(r < qry[i].first.second) {
      r++;
      ff[freq[arr[r]]]--;
      if(ff[freq[arr[r]]] == 0) tmp.push_back(freq[arr[r]]);
      freq[arr[r]]++;
      ff[freq[arr[r]]]++;
      if(ff[freq[arr[r]]] == 1) tmp.push_back(freq[arr[r]]);
    }
    while(l < qry[i].first.first) {
      ff[freq[arr[l]]]--;
      if(ff[freq[arr[l]]] == 0) tmp.push_back(freq[arr[l]]);
      freq[arr[l]]--;
      ff[freq[arr[l]]]++;
      if(ff[freq[arr[l]]] == 1) tmp.push_back(freq[arr[l]]);
      l++;
    }
    for(int z: tmp) {
      if(ff[z] > 0) all.insert(z);
      else if(all.count(z)) all.erase(z);
    }
    
    queue<pair<int, int> > ln; stack<pair<int, int> > rn;
    int m = 0;
    for(int x: all) {
      // {x, ff[x]}
      if(ff[x] / 2 > 0) {
        ln.push({x, ff[x] / 2});
        rn.push({x, ff[x] / 2});
        m += 2;
      }
      if(ff[x] % 2) {
        if(ln.size() > rn.size()) rn.push({x, 1});
        else ln.push({x, 1});
        m++;
      }
    }
    pair<int, int> b[m];
    int it = 0;
    while(ln.size()) {
      b[it++] = ln.front(); ln.pop();
    }
    while(rn.size()) {
      b[it++] = rn.top(); rn.pop();
    }
    int ans = 0;
    int ws=0,wps=0,tps=0,ps=0;
    for(int i=0; i<m; i++) {
      int F = b[i].first;
      int C = b[i].second;
      int t1 = C * F * ps * ws;
      int t2 = C * F * wps;
      int t3 = F * C * (C+1) / 2 * ws - F * C * tps / 2 + F * C * ws;
      ans += t1 - t2 + t3;
      ws += C * F;
      wps += C * F * ps;
      tps += C * F * (C + 1);
      ps += C;
    }
    for(int i=0; i<m; i++) {
      ans += b[i].first * (b[i].first + 1) / 2 * b[i].second;
      int totn = (b[i].second - 1) * b[i].second / 2 * (b[i].second + 1);
      totn -= b[i].second * (b[i].second - 1) * (2 * b[i].second - 1) / 6;
      ans += totn * b[i].first * b[i].first;
    }
    res[qry[i].second] = ans;
  }
  for(int i=1; i<=q; i++) cout << res[i] << "\n";

}
int32_t main() {
  ios::sync_with_stdio(0); cin.tie(0);
  int t = 1; //cin >> t;
  for(int i=1; i<=t; i++) solve(i);
}

Compilation message (stderr)

diversity.cpp: In function 'void solve(long long int)':
diversity.cpp:38:7: warning: unused variable 'c' [-Wunused-variable]
   38 |   int c = 300000;
      |       ^

• Subtask 1: 4 / 4
• Subtask 2: 10 / 10
• Subtask 3: 8 / 8
• Subtask 4: 16 / 16
• Subtask 5: 26 / 26
• Subtask 6: 36 / 36