Bit Manipulation Basics AND OR XOR NOT Left Right Shift in DSA Python - Practice Problems & Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this bitwise AND operation?

Consider the following Python code snippet:

result = 12 & 5
print(result)

What will be printed?

DSA Python

result = 12 & 5
print(result)

A 4

B 1

C 0

D 8

💡 Hint

Think about the binary form of 12 and 5 and where both have 1s.

12 in binary is 1100, 5 is 0101. Bitwise AND keeps bits set only where both are 1.

1100 & 0101 = 0100 which is 4 in decimal.

❓ Predict Output

intermediate

What is the output after left shifting?

What does this code print?

num = 3
result = num << 2
print(result)

DSA Python

num = 3
result = num << 2
print(result)

A 9

B 6

C 8

D 12

💡 Hint

Left shift by 2 means multiply by 2 twice.

3 in binary is 11. Left shifting by 2 adds two zeros: 1100 which is 12 decimal.

❓ Predict Output

advanced

What is the output of this XOR and NOT combination?

Analyze this code:

a = 10
b = 7
result = ~(a ^ b)
print(result)

What is printed?

DSA Python

a = 10
b = 7
result = ~(a ^ b)
print(result)

A 4

B 6

C -14

D -4

💡 Hint

First find XOR, then apply NOT (bitwise complement).

10 in binary is 1010, 7 is 0111. XOR: 1010 ^ 0111 = 1101 (13 decimal).

In Python, ~x = -x - 1, so ~13 = -14.

❓ Predict Output

advanced

What is the output after right shifting a negative number?

Consider this code:

num = -16
result = num >> 2
print(result)

What is printed?

DSA Python

num = -16
result = num >> 2
print(result)

A -4

B -8

C 4

D 8

💡 Hint

Right shift divides by 2, rounding down for negatives.

-16 in binary is represented in two's complement.

Right shifting by 2 divides by 4, rounding towards negative infinity.

-16 >> 2 = -4.

🧠 Conceptual

expert

How many bits are set to 1 after this operation?

Given the code:

num = 29
result = num & (num >> 1)
count = bin(result).count('1')
print(count)

What number is printed?

DSA Python

num = 29
result = num & (num >> 1)
count = bin(result).count('1')
print(count)

A 3

B 2

C 4

D 1

💡 Hint

Check binary of 29 and 29 shifted right by 1, then AND them.

29 in binary: 11101

29 >> 1: 01110 (14 decimal)

11101 & 01110 = 01100 (12 decimal)

Number of 1s in 01100 is 2.

Practice

1. What is the result of the bitwise AND operation between 5 and 3? (5 = 0101, 3 = 0011 in binary)

easy

A. 1

B. 7

C. 6

D. 0

Solution

1. Step 1: Convert numbers to binary

   5 in binary is 0101, 3 in binary is 0011.

2. Step 2: Perform bitwise AND

   0101 AND 0011 = 0001 (only bits set in both numbers remain set).

3. Final Answer:

   1 -> Option A

4. Quick Check:

   5 & 3 = 1 [OK]

Hint: AND keeps bits set in both numbers only [OK]

Common Mistakes:

• Confusing AND with OR operation
• Not converting numbers to binary before operation
• Assuming decimal addition instead of bitwise AND

2. Which of the following is the correct syntax to perform a left shift by 2 bits on variable x in Python?

easy

A. x <<< 2

B. x >> 2

C. x << 2

D. x >>| 2

Solution

1. Step 1: Understand left shift operator in Python

   Left shift is done using << operator, shifting bits to the left.

2. Step 2: Check syntax options

   Only x << 2 correctly shifts bits left by 2 places.

3. Final Answer:

   x << 2 -> Option C

4. Quick Check:

   Left shift uses << operator [OK]

Hint: Use << for left shift, >> for right shift [OK]

Common Mistakes:

• Using >>> which is not valid in Python
• Confusing left shift with right shift operator
• Using invalid operators like >>|

3. What is the output of the following Python code?

num = 12  # binary 1100
result = num >> 2
print(result)

medium

A. 6

B. 0

C. 48

D. 3

Solution

1. Step 1: Convert number and apply right shift

   12 in binary is 1100. Right shifting by 2 bits removes last two bits: 1100 >> 2 = 0011.

2. Step 2: Convert shifted binary back to decimal

   0011 in binary is 3 in decimal.

3. Final Answer:

   3 -> Option D

4. Quick Check:

   12 >> 2 = 3 [OK]

Hint: Right shift divides number by 2^shift count [OK]

Common Mistakes:

• Confusing right shift with left shift
• Not converting binary back to decimal
• Assuming shift multiplies instead of divides

4. Identify the error in the following code snippet:

value = 10
result = ~value << 1
print(result)

medium

A. Result is -22 due to operator precedence

B. RuntimeError due to invalid shift

C. Result is 21 due to incorrect bitwise NOT

D. SyntaxError due to incorrect operator usage

Solution

1. Step 1: Evaluate bitwise NOT and shift

   ~10 equals -11 (because ~x = -x-1). Then shifting left by 1 bit multiplies by 2: -11 << 1 = -22.

2. Step 2: Check operator precedence and final value

   Because ~ has higher precedence, ~10 is evaluated first, then shifted. So result is -22, but print shows -22.

3. Final Answer:

   Result is -22 due to operator precedence -> Option A

4. Quick Check:

   ~10 << 1 = -22 [OK]

Hint: Bitwise NOT flips bits, watch operator precedence [OK]

Common Mistakes:

• Assuming ~10 is positive
• Ignoring operator precedence between ~ and <<
• Expecting shift to apply before NOT

5. Given two integers a = 9 and b = 14, which expression will toggle the bits where a and b differ?

hard

A. a | b

B. a ^ b

C. a & b

D. ~a

Solution

1. Step 1: Understand toggling bits where numbers differ

   Toggling bits means flipping bits that are different between two numbers.

2. Step 2: Identify bitwise XOR operation

   XOR (^) returns 1 where bits differ and 0 where bits are same, effectively toggling differing bits.

3. Final Answer:

   a ^ b -> Option B

4. Quick Check:

   XOR toggles differing bits [OK]

Hint: XOR flips bits where inputs differ [OK]

Common Mistakes:

• Using AND or OR which do not toggle bits
• Confusing NOT (~) with XOR
• Assuming OR toggles bits