Two Non Repeating Elements in Array Using XOR in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the XOR result variable.

DSA C

int xor_result = [1];

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

A1

B0

C-1

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing xor_result to 1 or -1 causes incorrect XOR results.

Using NULL is invalid for integer initialization.

We start XOR with 0 because XOR with 0 leaves the number unchanged.

2fill in blank

medium

Complete the code to XOR all elements in the array.

DSA C

for (int i = 0; i < n; i++) {
    xor_result = xor_result [1] arr[i];
}

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

A^

B+

C&

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' adds numbers instead of XORing bits.

Using '&' or '|' performs AND or OR, not XOR.

The XOR operator in C is '^'. It combines bits where only one bit is set.

3fill in blank

hard

Fix the error in finding the rightmost set bit mask.

DSA C

int set_bit_mask = xor_result & [1] xor_result);

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

A~

B!

C-

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using bitwise NOT (~) instead of negation.

Using addition or logical NOT causes wrong mask.

To find the rightmost set bit, we AND xor_result with its two's complement (-xor_result).

4fill in blank

hard

Fill both blanks to separate the two unique numbers using the set bit mask.

DSA C

int num1 = 0, num2 = 0;
for (int i = 0; i < n; i++) {
    if (arr[i] & [1]) {
        num1 = num1 [2] arr[i];
    } else {
        num2 = num2 ^ arr[i];
    }
}

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

Aset_bit_mask

B^

C+

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of XOR causes wrong results.

Using '&' in place of XOR accumulates bits incorrectly.

We check if the element has the set bit using 'set_bit_mask'. Then XOR elements in each group separately.

5fill in blank

hard

Fill in the blank to print the two unique numbers in ascending order.

DSA C

if (num1 [1] num2) {
    printf("%d %d\n", num1, num2);
} else {
    printf("%d %d\n", num2, num1);
}

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

A<

B>

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' prints numbers in descending order.

Using '==' or '!=' is incorrect for ordering.

We print the smaller number first by comparing num1 and num2 with '<'.