1468F - Full Turn - CodeForces Solution

from math import gcd;from collections import Counter
for _ in range(int(input())):
    n = int(input());A = [list(map(int, input().split())) for _ in range(n)];cnt = Counter();ans = 0
    for a, b, c, d in A:x = c - a;y = d - b;g = gcd(x, y);x //= g;y //= g;ans += cnt[-x, -y];cnt[x, y] += 1
    print(ans)