Count number of pairs in array having sum divisible by K | SET 2 | Python Program to count pairs whose sum divisible by 'K ; Program to count pairs whose sum divisible by ' K ' ; Create a frequency array to count occurrences of all remainders when divided by K ; To store count of pairs . ; Traverse the array , compute the remainder and add k - remainder value hash count to ans ; Count number of ( A [ i ] , ( K - rem ) % K ) pairs ; Increment count of remainder in hash map ; Driver code
' NEW_LINE def countKdivPairs ( A , n , K ) : NEW_LINE INDENT freq = [ 0 for i in range ( K ) ] NEW_LINE ans = 0 NEW_LINE for i in range ( n ) : NEW_LINE INDENT rem = A [ i ] % K NEW_LINE ans += freq [ ( K - rem ) % K ] NEW_LINE freq [ rem ] += 1 NEW_LINE DEDENT return ans NEW_LINE DEDENT if __name__ == ' _ _ main _ _ ' : NEW_LINE INDENT A = [ 2 , 2 , 1 , 7 , 5 , 3 ] NEW_LINE n = len ( A ) NEW_LINE K = 4 NEW_LINE print ( countKdivPairs ( A , n , K ) ) NEW_LINE DEDENT