Check if Number is Even or Odd Using Bits in DSA Python - Practice Problems & Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this code using bitwise AND to check even or odd?

Look at the code below. It uses bitwise AND to check if a number is even or odd. What will it print?

DSA Python

def check_even_odd(num):
    if num & 1 == 0:
        print(f"{num} is Even")
    else:
        print(f"{num} is Odd")

check_even_odd(10)
check_even_odd(7)

A 10 is Even\n7 is Odd

B 10 is Odd\n7 is Even

C 10 is Odd\n7 is Odd

D 10 is Even\n7 is Even

💡 Hint

Remember, bitwise AND with 1 checks the last bit of the number.

The last bit of an even number is 0, so num & 1 == 0 means even. For odd numbers, last bit is 1.

❓ Predict Output

intermediate

What is the output of this function for negative numbers?

This function uses bitwise AND to check even or odd. What will it print for -4 and -3?

DSA Python

def check_even_odd(num):
    if num & 1 == 0:
        print(f"{num} is Even")
    else:
        print(f"{num} is Odd")

check_even_odd(-4)
check_even_odd(-3)

A -4 is Odd\n-3 is Odd

B -4 is Even\n-3 is Odd

C -4 is Odd\n-3 is Even

D -4 is Even\n-3 is Even

💡 Hint

Bitwise AND works the same for negative numbers in two's complement.

Negative numbers in two's complement keep the last bit for odd/even check. -4 ends with 0 bit, -3 ends with 1 bit.

🧠 Conceptual

advanced

Why does bitwise AND with 1 check if a number is even or odd?

Choose the best explanation why num & 1 == 0 means the number is even.

A Because bitwise AND with 1 converts the number to its negative form.

B Because bitwise AND with 1 counts the total number of bits in the number.

C Because bitwise AND with 1 shifts the number to the right by one bit.

D Because the last bit of an even number is always 0, so AND with 1 results in 0.

💡 Hint

Think about binary representation of even and odd numbers.

Even numbers end with 0 in binary, so AND with 1 (which is 0001) results in 0. Odd numbers end with 1, so AND with 1 results in 1.

🔧 Debug

advanced

What error does this code raise?

Look at this code that tries to check even or odd using bits. What error will it raise?

DSA Python

def check_even_odd(num):
    if num & 1 = 0:
        print(f"{num} is Even")
    else:
        print(f"{num} is Odd")

check_even_odd(5)

A NameError

B TypeError

C SyntaxError

D No error, prints '5 is Odd'

💡 Hint

Check the operator used in the if condition.

The code uses '=' instead of '==' in the if condition, which causes a SyntaxError.

🚀 Application

expert

How many numbers between 1 and 10 (inclusive) are identified as odd by this bitwise check?

Using the bitwise check num & 1 == 1 to find odd numbers, how many numbers between 1 and 10 (including both) will be identified as odd?

DSA Python

count = 0
for num in range(1, 11):
    if num & 1 == 1:
        count += 1
print(count)

A 5

B 6

C 4

D 10

💡 Hint

Count how many numbers have last bit 1 between 1 and 10.

Odd numbers between 1 and 10 are 1,3,5,7,9, total 5 numbers.