A40 - Triangle

提出

TLE

code: python

import itertools

from collections import Counter

n = int(input())

a = list(map(int, input().split()))

ans = 0

c = Counter(a)

for k, v in c.items():

if v >= 3:

ans += len(list(itertools.combinations(range(v), 3)))

print(ans)

解答

code: python

import itertools

from collections import Counter

n = int(input())

a = list(map(int, input().split()))

ans = 0

c = Counter(a)

for k, v in c.items():

if v >= 3:

ans += v * (v-1) * (v-2) // 6

print(ans)