text: Function to count quadruples of the required type
code: def countSubsequence ( a , n ) : NEW_LINE INDENT fill_counts ( a , n ) NEW_LINE answer = 0 NEW_LINE for i in range ( 1 , n ) : NEW_LINE INDENT for j in range ( i + 1 , n - 1 ) : NEW_LINE INDENT answer += ( lcount [ a [ j ] ] [ i - 1 ] * rcount [ a [ i ] ] [ j + 1 ] ) NEW_LINE DEDENT DEDENT return answer NEW_LINE DEDENT