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Add Codeforces Code

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Fengyi Chen
2024-02-15 22:52:21 +08:00
parent 8dbc0861b2
commit da903edacd
4 changed files with 45 additions and 0 deletions
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19
CodeForces/Forming Triangles.cpp Normal file
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#include<iostream>
using namespace std;
long long t, n, a[300005];
long long cnt[300005], s[300005], ans;
int main(){
ios::sync_with_stdio(0);
cin >> t;
while(t -- ){
cin >> n;
ans = 0;
for(int i = 0; i <= n; i ++ ) cnt[i] = s[i] = 0;
for(int i = 1; i <= n; i ++ ) cin >> a[i], cnt[a[i]] ++ ;
for(int i = 0; i <= n; i ++ ) ans += cnt[i] * (cnt[i] - 1) * (cnt[i] - 2) / 6, s[i] = (i == 0 ? 0 : s[i - 1]) + cnt[i];
for(int i = 1; i <= n; i ++ ) ans += cnt[i] * (cnt[i] - 1) / 2 * s[i-1];
cout << ans << "\n";
}
return 0;
}