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

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of Bitwise AND and OR Operations

What is the output of the following Java code snippet?

DSA Java

int a = 12;  // binary: 1100
int b = 10;  // binary: 1010
int andResult = a & b;
int orResult = a | b;
System.out.println("AND: " + andResult + ", OR: " + orResult);

A AND: 8, OR: 14

B AND: 4, OR: 14

C AND: 8, OR: 12

D AND: 4, OR: 12

💡 Hint

Remember to convert numbers to binary and apply AND and OR bit by bit.

The binary of 12 is 1100 and 10 is 1010.

AND operation: 1100 & 1010 = 1000 (decimal 8)

OR operation: 1100 | 1010 = 1110 (decimal 14)

❓ Predict Output

intermediate

Output of Bitwise XOR and NOT Operations

What will be printed by this Java code?

DSA Java

int x = 5;  // binary: 0101
int y = 3;  // binary: 0011
int xorResult = x ^ y;
int notX = ~x;
System.out.println("XOR: " + xorResult + ", NOT x: " + notX);

A XOR: 6, NOT x: 10

B XOR: 6, NOT x: -6

C XOR: 7, NOT x: -6

D XOR: 7, NOT x: 10

💡 Hint

XOR sets bits where bits differ. NOT flips all bits including sign bit.

5 in binary: 0101

3 in binary: 0011

XOR: 0101 ^ 0011 = 0110 (decimal 6)

NOT 5 flips bits: ~0101 = 1010 (in 32-bit signed int, this is -6)

❓ Predict Output

advanced

Result of Left and Right Shift Operations

What is the output of this Java code snippet?

DSA Java

int num = 16;  // binary: 0001 0000
int leftShift = num << 2;
int rightShift = num >> 3;
System.out.println("Left Shift: " + leftShift + ", Right Shift: " + rightShift);

A Left Shift: 32, Right Shift: 2

B Left Shift: 64, Right Shift: 1

C Left Shift: 64, Right Shift: 2

D Left Shift: 32, Right Shift: 1

💡 Hint

Left shift multiplies by 2^n, right shift divides by 2^n (floor division).

16 << 2 = 16 * 4 = 64

16 >> 3 = 16 / 8 = 2

🧠 Conceptual

advanced

Understanding Bitwise NOT on Negative Numbers

In Java, what is the result of applying the bitwise NOT (~) operator to -1?

A -2

B 1

C 0

D -0

💡 Hint

Consider two's complement representation of -1 and how NOT flips bits.

-1 in binary (32-bit) is all 1s: 11111111 11111111 11111111 11111111

Applying ~ flips all bits to 0s: 00000000 00000000 00000000 00000000 which is 0, but since ~x = -x - 1, ~(-1) = 0

Wait, this is a trick: actually ~(-1) = 0, but the question asks for the result of ~(-1), which is 0.

Correction: The correct answer is 0, so option A.

❓ Predict Output

expert

Output of Combined Bitwise Operations

What is the output of this Java code snippet?

DSA Java

int a = 9;   // binary: 1001
int b = 14;  // binary: 1110
int result = ((a & b) ^ (a | b)) << 1;
System.out.println(result);

A 22

B 28

C 30

D 14

💡 Hint

Calculate AND, OR, XOR step by step, then apply left shift.

a & b = 1001 & 1110 = 1000 (8)

a | b = 1001 | 1110 = 1111 (15)

(a & b) ^ (a | b) = 8 ^ 15 = 7 (0111)

Left shift by 1: 7 << 1 = 14 (1110)

Wait, this is 14, but options show 28 as C.

Recalculate carefully:

8 ^ 15 = 7

7 << 1 = 14

So output is 14, option D.

But option D is 14, option D is 28.

Check if code is correct or if parentheses are different.

Code: ((a & b) ^ (a | b)) << 1

Yes, result is 14.

So correct answer is A.

Practice

1. What does the bitwise AND operator (&) do when applied to two bits?

easy

A. Flips the bits from 0 to 1 and 1 to 0

B. Returns 1 if at least one bit is 1

C. Returns 1 only if both bits are 1

D. Returns 0 only if both bits are 0

Solution

1. Step 1: Understand bitwise AND operation

   The AND operator compares each bit of two numbers and returns 1 only if both bits are 1.

2. Step 2: Apply to example bits

   For bits 1 & 1, result is 1; for 1 & 0 or 0 & 1 or 0 & 0, result is 0.

3. Final Answer:

   Returns 1 only if both bits are 1 -> Option C

4. Quick Check:

   AND = 1 only if both bits 1 [OK]

Hint: AND returns 1 only when both bits are 1 [OK]

Common Mistakes:

• Confusing AND with OR operator
• Thinking AND flips bits
• Assuming AND returns 1 if any bit is 1

2. Which of the following is the correct syntax for left shifting an integer variable x by 3 positions in Java?

easy

A. x << 3;

B. x >> 3;

C. x <<< 3;

D. x >>> 3;

Solution

1. Step 1: Recall left shift operator syntax in Java

   Left shift operator is << and shifts bits to the left.

2. Step 2: Identify correct usage

   To shift variable x left by 3 bits, use x << 3;. Other options are right shifts or invalid.

3. Final Answer:

   x << 3; -> Option A

4. Quick Check:

   Left shift = x << number [OK]

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

Common Mistakes:

• Using >>> for left shift (it's unsigned right shift)
• Using <<< which is invalid syntax
• Confusing left and right shift operators

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

int a = 5;  // binary 0101
int b = 3;  // binary 0011
int c = a ^ b;
System.out.println(c);

medium

A. 8

B. 7

C. 2

D. 6

Solution

1. Step 1: Convert numbers to binary

   a = 5 is 0101, b = 3 is 0011 in binary.

2. Step 2: Apply XOR operation bitwise

   XOR returns 1 if bits differ, 0 if same.
   0101 XOR 0011 = 0110 (binary) which is 6 decimal.

3. Final Answer:

   6 -> Option D

4. Quick Check:

   5 ^ 3 = 6 [OK]

Hint: XOR sets bits where inputs differ [OK]

Common Mistakes:

• Confusing XOR with OR or AND
• Calculating XOR incorrectly bitwise
• Assuming XOR adds numbers

4. Identify the error in the following Java code snippet:

int x = 8;
int y = ~x << 2;
System.out.println(y);

medium

A. No error; the code runs and prints a valid integer

B. The shift operator << must be used before the NOT operator ~

C. The bitwise NOT operator (~) cannot be used on integers

D. The variable y should be declared as long instead of int

Solution

1. Step 1: Analyze bitwise NOT and shift usage

   The NOT operator (~) flips all bits of x. Then the result is shifted left by 2 bits.

2. Step 2: Check Java syntax and types

   Both ~ and << operators work on int type. The expression is valid and prints an integer.

3. Final Answer:

   No error; the code runs and prints a valid integer -> Option A

4. Quick Check:

   ~ and << valid on int [OK]

Hint: Bitwise NOT and shifts work fine on int in Java [OK]

Common Mistakes:

• Thinking ~ cannot be used on int
• Assuming operator order is wrong
• Believing int can't hold shifted values

5. Given an integer n, which expression correctly toggles (flips) the 4th bit (counting from 0) of n using bitwise operators in Java?

hard

A. n = n | (1 << 4);

B. n = n ^ (1 << 4);

C. n = n & ~(1 << 4);

D. n = ~n << 4;

Solution

1. Step 1: Understand toggling a bit

   Toggling means flipping the bit: 0 becomes 1, 1 becomes 0.

2. Step 2: Identify correct operator for toggling

   XOR (^) with 1 at the bit position flips that bit. So n ^ (1 << 4) toggles the 4th bit.

3. Final Answer:

   n = n ^ (1 << 4); -> Option B

4. Quick Check:

   Toggling bit uses XOR with mask [OK]

Hint: Use XOR with mask to toggle bits [OK]

Common Mistakes:

• Using OR to toggle (only sets bit)
• Using AND with negation to toggle (clears bit)
• Using NOT and shift incorrectly