Why Bit Manipulation and When It Beats Arithmetic in DSA C - Test Your Knowledge

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a number is even using bit manipulation.

DSA C

int isEven(int num) {
    return (num & [1]) == 0;
}

Drag options to blanks, or click blank then click option'

A1

B0

C2

Dnum

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 in the bitwise AND which always returns 0.

Using 2 which checks the second bit, not the first.

The least significant bit (LSB) of an even number is 0. Using num & 1 checks this bit.

2fill in blank

medium

Complete the code to multiply a number by 8 using bit manipulation.

DSA C

int multiplyByEight(int num) {
    return num [1] 3;
}

Drag options to blanks, or click blank then click option'

A+

B*

C>>

D<<

Attempts:

3 left

💡 Hint

Common Mistakes

Using right shift which divides the number.

Using multiplication operator instead of bit shift.

Left shifting a number by 3 bits multiplies it by 2³ = 8.

3fill in blank

hard

Fix the error in the code to divide a number by 4 using bit manipulation.

DSA C

int divideByFour(int num) {
    return num [1] 2;
}

Drag options to blanks, or click blank then click option'

A>>

B<<

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using left shift which multiplies instead of dividing.

Using addition or subtraction operators.

Right shifting by 2 bits divides the number by 2² = 4.

4fill in blank

hard

Fill both blanks to toggle the 3rd bit of a number.

DSA C

int toggleThirdBit(int num) {
    return num [1] [2];
}

Drag options to blanks, or click blank then click option'

A^

B&

C1 << 2

D1 << 3

Attempts:

3 left

💡 Hint

Common Mistakes

Using bit 3 (index 3) instead of bit 2 for the 3rd bit.

Using AND which clears bits instead of toggling.

XOR (^) with 1 << 2 toggles the 3rd bit (bit index 2).

5fill in blank

hard

Fill all three blanks to set the 5th bit of a number and clear the 2nd bit.

DSA C

int setAndClearBits(int num) {
    num = num [1] [2];
    num = num [3] ~(1 << 1);
    return num;
}

Drag options to blanks, or click blank then click option'

A|

B&

C~

D1 << 4

Attempts:

3 left

💡 Hint

Common Mistakes

Using XOR to clear bits which toggles instead.

Using wrong bit positions for setting or clearing.

Use OR (|) with 1 << 4 to set the 5th bit, then AND (&) with the negation (~) of 1 << 1 to clear the 2nd bit.