Submission #622370

#	Time	Username	Problem	Language	Result	Execution time	Memory
622370		Joshc	Diversity (CEOI21_diversity)	C++11	100 / 100	3676 ms	6560 KiB

diversity

#include <bits/stdc++.h>
using namespace std;
 
#define scan(x) do{while((x=getchar())<'0'); for(x-='0'; '0'<=(_=getchar()); x=(x<<3)+(x<<1)+_-'0');}while(0)
char _;
 
#define ll long long
 
int cnt[300005], a[300005], l[300005], r[300005];
ll n, out[50005];
const int SQRT = 900;
 
ll f(ll a, ll b, ll x) {
    // sum((a+bi) choose 2) with x terms
    return x*a*a + a*b*x*(x-1) + x*(x-1)*(2*x-1)/6*b*b - (2*a+b*(x-1))*x/2;
}
 
ll val(ll start, ll sz, ll num) {
    // We have num blocks of size sz, starting at position start
    // What is the total contribution?
    if (!num || !sz) return 0;
    ll res = n*(n+1)*num;
    res -= f(start, sz, num);
    res -= f(n-(start+sz*num-1)+1, sz, num);
    return res/2;
}
 
bool comp(int x, int y) {
    int p = l[x]/SQRT, q = l[y]/SQRT;
    if (p != q) return p < q;
    return p&1 ? (r[x] < r[y]) : (r[x] > r[y]);
}
 
vector<int> s;
bool included[300005];
int freq[300005], v[300005];
 
void add(int x) {
    if (freq[x] && !--v[freq[x]]) included[freq[x]] = false;
    v[++freq[x]]++;
    if (!included[freq[x]]) {
        included[freq[x]] = true;
        s.push_back(freq[x]);
    }
}
 
void remove(int x) {
    if (!--v[freq[x]]) included[freq[x]] = false;
    v[--freq[x]]++;
    if (!included[freq[x]]) {
        included[freq[x]] = true;
        s.push_back(freq[x]);
    }
}
 
ll solve() {
    ll ans = 0;
    int lsum = 0, rsum = 0;
    sort(s.begin(), s.end());
    vector<int> cur;
    for (int sz : s) {
        if (!included[sz]) continue;
        included[sz] = false;
        cur.push_back(sz);
        int num = v[sz];
        int lv = 0, rv = 0;
        if (lsum < rsum) {
            lv = num-num/2;
            rv = num/2;
        } else {
            rv = num-num/2;
            lv = num/2;
        }
        ans += val(lsum+1, sz, lv) + val(rsum+1, sz, rv);
        lsum += sz*lv;
        rsum += sz*rv;
    }
    s = cur;
    for (int i : s) included[i] = true;
    return ans;
}
 
int main() {
    int q, x;
    scan(n);
    scan(q);
    vector<int> order;
    for (int i=1; i<=n; i++) scan(a[i]);
    for (int i=1; i<=q; i++) {
        scan(l[i]);
        scan(r[i]);
        order.push_back(i);
    }
    sort(order.begin(), order.end(), comp);
    
    int L = 1, R = 0;
 
    for (int i : order) {
        while (R < r[i]) add(a[++R]);
        while (L > l[i]) add(a[--L]);
        while (R > r[i]) remove(a[R--]);
        while (L < l[i]) remove(a[L++]);
        n = R-L+1;
        out[i] = solve();
    }
 
    for (int i=1; i<=q; i++) printf("%lld\n", out[i]);
}

Compilation message (stderr)

diversity.cpp: In function 'int main()':
diversity.cpp:84:12: warning: unused variable 'x' [-Wunused-variable]
   84 |     int q, x;
      |            ^

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