for _ in range(int(input())):
n = int(input())
ai = list(map(int, input().split()))
mean_2 = (2*sum(ai))/n
d = {}
output = 0
for i in ai:
output+= d.get(i,0)
d[mean_2 - i] = d.get(mean_2-i,0) + 1
print(output)
#include <bits/stdc++.h>
using namespace std;
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define dbg(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define dbg(x...)
#endif
/* stop freaking out pls */
void solve(){
int n;
cin >> n;
vector<long long> a(n);
map<long long, long long> f;
long long sum = 0;
for (auto &u : a) {
cin >> u;
sum += u;
f[u]++;
}
sum <<= 1;
if (sum%n) {
cout << 0 << '\n';
return;
}
sum /= n;
long long ans = 0;
for (int i = 0; i < n; i++) {
f[a[i]]--;
long long v = sum - a[i];
ans += f[v];
}
cout << ans << '\n';
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int tt;
cin >> tt;
while(tt--){
solve();
}
}
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450. Delete Node in a BST | 445. Add Two Numbers II |
442. Find All Duplicates in an Array | 437. Path Sum III |
436. Find Right Interval | 435. Non-overlapping Intervals |
406. Queue Reconstruction by Height | 380. Insert Delete GetRandom O(1) |
332. Reconstruct Itinerary | 368. Largest Divisible Subset |
377. Combination Sum IV | 322. Coin Change |
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274. H-Index | 260. Single Number III |
240. Search a 2D Matrix II | 238. Product of Array Except Self |
229. Majority Element II | 222. Count Complete Tree Nodes |