CommonElements

array1 = [1,2,3,4]
array2 = [5,6,3,8]

def common_elements(inp1,inp2):
    lookup_set = set(inp1)
    common_array = []
    
    for i in inp2:
        if i in lookup_set:
            common_array.append(i)
    return common_array 



print(common_elements(array1,array2))