Ex1 Count elements in the array arr length len arr print Elements coun

# Ex1: Count elements in the array
arr = [1, 3, 5, 6]
length = len(arr)
print('Elements count:')
print(length)


# Ex2: Count elements equal to defined
def equal_num(arr, num):
    count = 0
    for i in arr:
        if i == num:
            count += 1
    return count


print('Count elements equal to 2:')
equal_res = equal_num([1, 2, 1, 2, 1, 3], 2)
print(equal_res)


# Ex3: Sum all elements in the array
arr2 = [1, 3, 5, 6, 8]
sum_arr = sum(arr2)
print('Sum of array:')
print(sum_arr)

# Ex4: Find max of elements in the array
print('Max of array:')
print(max(arr2))


# Ex5: Find mean of elements in the array
print('Mean of array:')
print(sum(arr2) / len(arr2))

# Ex6: Write elements with space as delimiter
print('Splitted string:')
print(' '.join(str(i) for i in arr2))

# Ex7: Multiply numbers on even positions by 2
# and numbers on odd positions by 3
arr3 = []
for i in range(0, len(arr2)):
    if i % 2 == 0:
        arr3.append(arr2[i]*2)
    else:
        arr3.append(arr2[i]*3)
print('Multiplied values:')
print(arr3)


# Ex8: Check if all elements in the array are multiple of a number.
def multiple_num(arr, num):
    for i in arr:
        if i % 7 != 0:
            return False
    return True


arr4 = [7, 0, 14, 210]
print('Multiple of a 7:')
print(multiple_num(arr2, 7))
print(multiple_num(arr4, 7))


# Ex9: check if there is a negative number in the array
arr5 = [1, 3, -5, 6, 8]


def is_negative(arr):
    for i in arr:
        if i < 0:
            return True
    return False


print('Contains negative:')
print(is_negative(arr))
print(is_negative(arr5))


# Ex10: Leave only even numbers in the array
def only_even(arr):
    evens = []
    for i in arr:
        if i % 2 == 0:
            evens.append(i)
    return evens


evens = only_even(arr2)
print("Only even numbers:")
print(evens)

# Ex11: Split string into words
str = "quick brown fox jumps over the lazy dog"
splits = str.split(" ")
print("Splitted string:")
print(splits)

# Ex12: Return list starting from 5th element.
arr6 = [1, 3, 5, 6, 8, 7, 12, 1111, 19]
print("Elements starting from 5th:")
print(arr6[5:])

# Ex13: Return list excluding first and last element.
print('Elements excluding first and last:')
print(arr6[1:-1])