Submission #5493457

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Source Code Expand

N,m=map(int,input().split())

X=list(map(int,input().split()))

#print(X)

M=[[]for i in range(m)]
for i in range(N):
    M[X[i]%m].append(X[i])
    
#print(M)

ans=len(M[0])//2
if m%2==0:
    ans+=len(M[m//2])//2
#print(0,ans)
for i in range(1,(m//2)+1):
    if m%2==0:
        if i==(m//2):
            break
    ans+=min(len(M[i]),len(M[m-i]))
    #print(i,ans)
    L=[0]
    cnt=1
    if len(M[i])>len(M[m-i]):
        A=M[i]
    else:
        A=M[m-i]
    for j in range(1,max(len(M[i]),len(M[m-i]))):
        if A[j]==A[j-1]:
            cnt+=1
        else:
            L.append(cnt//2)
            cnt=1
    L.append(cnt//2)
    #print(L)
    if (abs(len(M[i])-len(M[m-i]))//2)<=sum(L):
        ans+=(abs(len(M[i])-len(M[m-i]))//2)
    else:
        ans+=sum(L)
    #print(i,ans)
print(ans)

Submission Info

Judge Result