Submission #526206

#	Time	Username	Problem	Language	Result	Execution time	Memory
526206		Plurm	Diversity (CEOI21_diversity)	C++11	64 / 100	7096 ms	17088 KiB

diversity

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;

template <typename T>
class FenwickTree{
public:
  T* FT;
  int n;
  bool negmode;
  FenwickTree(int sz = 1 << 19, bool negindex = true){
    n = sz+505;
    FT = new T[n];
    fill(FT, FT+n, (T)0);
    negmode = negindex;
  }
  void add(int idx, T amt){
    if(negmode) idx += n/2;
    while(idx < n){
      FT[idx] += amt;
      idx += idx & -idx;
    }
  }
  T sum(int idx){
    if(negmode) idx += n/2;
    T ret = (T)0;
    while(idx > 0){
      ret += FT[idx];
      idx -= idx & -idx;
    }
    return ret;
  }
  int lower_bound(const int v){
    if(v > FT[1]) return 0;
    int cur = 1 << 18;
    int part = FT[cur];
    for(int i = 17; i >= 0; i--){
      if(part >= v){
        cur += 1 << i;
        part += FT[cur];
      }else{
        part -= FT[cur];
        cur -= 1 << i;
        part += FT[cur];
      }
    }
    if(part < v) return cur-1;
    return cur;
  }
  int upper_bound(const int v){
    return lower_bound(v+1);
  }
};

FenwickTree<int> FT1; // Ri
FenwickTree<long long> FT2; // Ri * i
int cnt[300005];
int a[300005];
// abstract deque
// fenwick indexing:
// [...] [-3] [-2] [-1] [0] [1] [2] [...]
// deque indexing:
// [...] [6] [4] [2] [1] [3] [5] [...]
// invariant:
// dq[-i] <= dq[i] for all positive i
// dq[-i] >= dq[i+1] for all positive i

int dq2fw(int idx){
  return idx/2 * (idx % 2 ? 1 : -1);
}

FenwickTree<int> dq(300000, false); // using deque indexing
long long deque_add(const int x){
  int idx = dq.upper_bound(x)+1;
  dq.add(idx, 1);
  dq.add(idx+1, -1);
  int b = dq2fw(idx);
  FT1.add(b, 1);
  FT2.add(b, b);
  return FT2.FT[1 << 19] - FT2.sum(b) - 1ll * (b-1) * (FT1.FT[1 << 19] - FT1.sum(b))
  + 1ll * (b+1) * FT1.sum(b-1) - FT2.sum(b-1) + x+1;
}
long long deque_remove(const int x){
  int idx = dq.lower_bound(x);
  dq.add(idx, -1);
  dq.add(idx+1, 1);
  int b = dq2fw(idx);
  FT1.add(b, -1);
  FT2.add(b, -b);
  return FT2.FT[1 << 19] - FT2.sum(b) - 1ll * (b-1) * (FT1.FT[1 << 19] - FT1.sum(b))
  + 1ll * (b+1) * FT1.sum(b-1) - FT2.sum(b-1) + x;
}

vector<tuple<int,int,int>> qbckt[300005]; // (L, R, Q)
long long answer[50005];
int qcnt[2048];

int main(){
	int n,q;
	scanf("%d%d",&n,&q);
	for(int i = 1; i <= n; i++){
		scanf("%d",a+i);
	}
  int SQRT = n/sqrt(q);
  vector<pair<int,int>> rawq;
  for(int i = 0; i < q; i++){
    int l, r;
    scanf("%d%d",&l,&r);
    rawq.emplace_back(l,r);
    qcnt[l/SQRT]++;
  }
  for(int i = 0; i <= n/SQRT+2; i++){
    qbckt[i].reserve(qcnt[i]);
  }
  for(int i = 0; i < q; i++){
    int l, r;
    tie(l, r) = rawq[i];
    qbckt[l / SQRT].emplace_back(l, r, i);
  }
  int lptr = 1;
  int rptr = 0;
  long long ans = 0ll;
  for(int i = 0; i <= n/SQRT+2; i++){
    sort(qbckt[i].begin(), qbckt[i].end(), [](tuple<int,int,int> x, tuple<int,int,int> y){
      return get<1>(x) < get<1>(y);
    });
    // Below goes declaratively.
    for(auto qr : qbckt[i]){
      int l, r, qnum;
      tie(l, r, qnum) = qr;
      while(rptr < r){
        rptr++;
        ans += deque_add(cnt[a[rptr]]);
        cnt[a[rptr]]++;
      }
      while(lptr > l){
        lptr--;
        ans += deque_add(cnt[a[lptr]]);
        cnt[a[lptr]]++;
      }
      while(lptr < l){
        ans -= deque_remove(cnt[a[lptr]]);
        cnt[a[lptr]]--;
        lptr++;
      }
      while(rptr > r){
        ans -= deque_remove(cnt[a[rptr]]);
        cnt[a[rptr]]--;
        rptr--;
      }
      answer[qnum] = ans;
    }
  }
  for(int i = 0; i < q; i++){
    printf("%lld\n", answer[i]);
  }
	return 0;
}

Compilation message (stderr)

diversity.cpp: In function 'int main()':
diversity.cpp:100:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  100 |  scanf("%d%d",&n,&q);
      |  ~~~~~^~~~~~~~~~~~~~
diversity.cpp:102:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |   scanf("%d",a+i);
      |   ~~~~~^~~~~~~~~~
diversity.cpp:108:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |     scanf("%d%d",&l,&r);
      |     ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 10 / 10
• Subtask 3: 8 / 8
• Subtask 4: 16 / 16
• Subtask 5: 26 / 26
• Subtask 6: 0 / 36