Absolute Distinct Numbers - c++

Question

I am writing an exercises on codility via c++. Here the question:
A non-empty zero-indexed array A consisting of N numbers is given. The
array is sorted in non-decreasing order. The absolute distinct count
of this array is the number of distinct absolute values among the
elements of the array.
For example, consider array A such that:
A[0] = -5
A[1] = -3
A[2] = -1
A[3] = 0
A[4] = 3
A[5] = 6
The absolute distinct count of this array is 5, because there are 5 distinct absolute values among the elements of this array,
namely 0, 1, 3, 5 and 6.
Write a function:
int solution(vector<int> &A);
that, given a non-empty zero-indexed array A consisting of N numbers,
returns absolute distinct count of array A.
For example, given array A such that:
A[0] = -5
A[1] = -3
A[2] = -1
A[3] = 0
A[4] = 3
A[5] = 6
the function should return 5, as explained above.
Assume that:
N is an integer within the range [1..100,000];
each element of array A
is an integer within the range [−2,147,483,648..2,147,483,647];
array
A is sorted in non-decreasing order.
Complexity:
expected worst-case time complexity is O(N);
expected worst-case space
complexity is O(N), beyond input storage (not counting the storage
required for input arguments).
Elements of input arrays can be
modified.
I am writing down the following code, and I fail to find any problems in my code, but it just doesn't pass.
#include <algorithm>
#include <vector>
#include <cmath>
int solution(vector<int> &A) {
int N(A.size());
vector<long long> B(N,0);
int counter(1);
//int index(0);
int move1(0);
int move2(N-1);
if(N==1)
{return 1;}
if(N==0)
{return 0;}
if(N==2)
{
if(abs(A[0])==abs(A[1]))
{return 1;}
else{return 2;}
}
for (int i = 0 ; i < N ; ++i)
{
B[i]=abs((long long )A[i]);
}
while(move1<move2)
{
if(B[move1]==B[move1+1])
{move1+=1;}
else if(B[move2]==B[move2]-1)
{move2-=1;}
else if(B[move1]>B[move2])
{
counter+=1;
move1+=1;
}
else if(B[move1]<B[move2])
{
counter+=1;
move2-=1;
}
else{move1+=1;}
}
return counter;
}
Here's the link of performance, https://codility.com/demo/results/trainingUT9QAN-JMM/
There's some errors but I can't figure out its detail, if anyone could help me with my code, I will really appreciate!
Thanks!

Answer 1

You may want to have an iterative solution. Start from both ends and work your way inward toward 0.
#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
size_t solution( const std::vector< int > & A )
{
std::vector< int >::const_iterator f( A.begin() );
std::vector< int >::const_reverse_iterator b( A.rbegin() );
size_t result = 0;
if( A.size() )
for( ; ( f != A.end() ) && ( b != A.rend() ); )
{
if( *f >= 0 )
return result + ( ( A.end() - f ) - ( b - A.rbegin() ) );
else if( *b <= 0 )
return result + ( ( A.rend() - b ) - ( f - A.begin() ) );
else if( *f == -*b )
++result, ++f, ++b;
else if( *f > -*b )
++result, ++b;
else
++result, ++f;
}
return result;
}
int main( int, char ** )
{
std::cout << solution( std::vector< int >{ -5, -3, -1, 0, 3, 6} ) << std::endl;
std::cout << solution( std::vector< int >{ -5, -3, -1, 0, 1, 3, 6} ) << std::endl;
std::cout << solution( std::vector< int >{ -5, -3, -1, 0, 2, 3, 6} ) << std::endl;
std::cout << solution( std::vector< int >{ -5, -3, -1, 3, 6} ) << std::endl;
std::cout << solution( std::vector< int >{ -5, -3, -1, 0, 3, 4, 5} ) << std::endl;
return 0;
}

Answer 2

100% solution with Ruby
def solution(a)
a.each_with_object({}){ |el, acc| acc[el.abs] = true }.size
end

Answer 3

Got 100/100 using Java 8 streams.
return (int) Arrays.stream(A).map(Math::abs)
.distinct().count();

Answer 4

def solution(A):
# Creates an empty hashset
s = set()
n = len(A)
res = 0
for i in range(n):
# If not present, then put it in
# hashtable and increment result
if (A[i] not in s):
s.add(A[i])
res += 1
return res