This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
// Make the best become better
// No room for laziness
#include<bits/stdc++.h>
#define int long long
#define pb push_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 2e5 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n, a[maxN];
vector<int> pos[maxN];
const int block_size = 2000;
void ReadInput()
{
cin >> n;
vector<int> vc;
for(int i=1; i<=n; i++)
{
cin >> a[i];
vc.pb(a[i]);
}
sort(vc.begin(), vc.end());
vc.erase(unique(vc.begin(), vc.end()), vc.end());
for(int i=1; i<=n; i++)
a[i] = upper_bound(vc.begin(), vc.end(), a[i]) - vc.begin();
for(int i=1; i<=n; i++)
pos[a[i]].pb(i);
}
int res = 0;
void Cal1(int val)
{
for(int i=0; i<pos[val].size(); i++)
{
for(int j=i; j>=0; j--)
{
// i = 2, j = 0;
int r = pos[val][i], l = pos[val][j];
int s = 2 * (i - j + 1) - (r - l + 1);
if(s <= 0) continue;
int last1 = j ? pos[val][j - 1] : 0;
int last2 = i == pos[val].size() - 1 ? n + 1 : pos[val][i + 1];
int left = s - 1;
int t1 = l - last1 - 1, t2 = last2 - r - 1;
t1 = min(t1, left);
t2 = min(t2, left);
/// cal 0 <= x1 <= t1, 0 <= x2 <= t2, x1 + x2 <= left
if(t1 + t2 <= left) res += (t1 + 1) * (t2 + 1);
else
{
res += (t2 + 1) * (left - t2);
int t = min(t1 - (left - t2), t2 - 1);
res += (t + 2) * (t + 1) / 2;
}
// cout << res;exit(0);
}
}
}
void Cal2(int val)
{
}
void Solve()
{
for(int i=1; i<=n; i++)
{
if(pos[i].empty()) continue;
if(pos[i].size() < block_size) Cal1(i);
else Cal2(i);
}
cout << res;
}
int32_t main()
{
//freopen("sol.inp", "r", stdin);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
ReadInput();
Solve();
}
Compilation message (stderr)
Main.cpp: In function 'void Cal1(long long int)':
Main.cpp:39:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
39 | for(int i=0; i<pos[val].size(); i++)
| ~^~~~~~~~~~~~~~~~
Main.cpp:48:27: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
48 | int last2 = i == pos[val].size() - 1 ? n + 1 : pos[val][i + 1];
| ~~^~~~~~~~~~~~~~~~~~~~~~
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