我如何优化此代码到一个循环或最小的可能

Question

I need to restrict this code to maximum one loop or fewer if possible:

for i in range(1,count+1):

  for j in range(i+1,count+1):

     newcount+=1

Basically what it does is find possible combinations without repition .

Answer 1

It looks like a triangular number between 1 and count - 1 :

count * (count - 1) // 2

Here's a small test:

count = 10
newcount = 0

for i in range(1,count+1):
  for j in range(i+1,count+1):
     newcount+=1

print(newcount)
# 45
print(newcount == count * (count - 1) // 2)
# True

Answer 2

I would recommend itertools.combinations

In your case, you can iterator over itertools.combinations(xrange(1, count+1), 2)