Maximum subset which has no sum of two divisible by K

Question

I am given the set {1, 2, 3, ... ,N}. I have to find the maximum size of a subset of the given set so that the sum of any 2 numbers from the subset is not divisible by a given n

Answer 1

n,k=(raw_input().split(' '))
n=int(n)
k=int(k)
l=[0 for x in range(k)]
d=[int(x) for x in raw_input().split(' ')]
flag=0
for x in d:
   l[x%k]=l[x%k]+1

sum=0

if l[0]!=0:
    sum+=1 
if (k%2==0):
    sum+=1


if k==1:
    print 1
elif k==2:
    print 2 
else:       
    i=1
    j=k-1
    while i=l[j] else l[j])
        i=i+1
        j=j-1
     print sum