I can not understand the cycle of the program?

Question

Python

spisok = [1, 2, 3, 2, 3]
print(spisok)
spisok.sort()
n = len(spisok)
i=0
for l in range(n-1):
    for j in range(n-l-1):
        if spisok[j]==spisok[j+1]:
            i+=1
print(i)

To find the pairs, I used the bubble method, but I can't figure out why the number of pairs is not correct. Suppose in this code it shows that there are 4 pairs, not 2. But in the code where all elements are the same and there are five of them, it correctly calculates the number of pairs - 10.

Answer 1

If I understand the purpose correctly, then something like this should be:

for l in range(n-1):
    for j in range(l+1, n):
        if spisok[l]==spisok[j]:
            i+=1