Count of permutations such that sum of K numbers from given range is even | Function to return the number of all permutations such that sum of K numbers in range is even ; Find total count of even and odd number in given range ; Iterate loop k times and update even_sum & odd_sum using previous values ; Update the prev_even and odd_sum ; Even sum ; Odd sum ; Return even_sum ; Given ranges ; Length of permutation ; Function call
def countEvenSum ( low , high , k ) : NEW_LINE INDENT even_count = high / 2 - ( low - 1 ) / 2 NEW_LINE odd_count = ( high + 1 ) / 2 - low / 2 NEW_LINE even_sum = 1 NEW_LINE odd_sum = 0 NEW_LINE for i in range ( 0 , k ) : NEW_LINE INDENT prev_even = even_sum NEW_LINE prev_odd = odd_sum NEW_LINE even_sum = ( ( prev_even * even_count ) + ( prev_odd * odd_count ) ) NEW_LINE odd_sum = ( ( prev_even * odd_count ) + ( prev_odd * even_count ) ) NEW_LINE DEDENT print ( int ( even_sum ) ) NEW_LINE DEDENT low = 4 ; NEW_LINE high = 5 ; NEW_LINE K = 3 ; NEW_LINE countEvenSum ( low , high , K ) ; NEW_LINE