볼링공 고르기

p.315

 

방법 1

N,M=map(int, input().split())
weight=list(map(int, input().split()))

count=0

for i in range(N):
  for j in range(i,N):
    if weight[i]!=weight[j]:
      count+=1

print(count)

 

방법 2

N,M=map(int, input().split())
weight=list(map(int, input().split()))

count=0

array=[0]*(M+1)

for i in range(N):
  array[weight[i]]+=1

for j in range(1, M+1):
  N -= array[j]
  count += array[j]*N

print(count)