Submission #3494566

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Source Code Expand

from collections import Counter as C
def gcd(a, b):
    if b == 0:
        return a
    else:
        return gcd(b, a % b)
T = [[0, 1], [1, 0]]
for i in range(1, 26):
    for j in range(1, 26):
        if gcd(i,j) == 1:
            T.append([i, j])
            T.append([i, -j])
N = int(input())
X = []
for i in range(N):
    x, y = map(int, input().split())
    X.append([x, y])

def exc(c):
    ret = 0
    if c >= 4:
        ret += (c*(c-1)*(c-2)*(c-3))//24
    if c>= 3:
        ret += ((c*(c-1)*(c-2))//6) * (N-c)
    return ret

ans = (N*(N-1)*(N-2)*(N-3))//24

for a, b in T:
    Y = C([a * x[0] + b * x[1] for x in X]).values()
    for y in Y:
        if y >= 3:
            ans -= exc(y)
print (ans)

Submission Info

Judge Result