Find the Only Non Repeating Element Using XOR in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the variable that will hold the XOR result.

DSA C

int unique = [1];

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A-1

B1

C0

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing unique with 1 or -1 causes wrong results.

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

2fill in blank

medium

Complete the for loop to iterate over the array elements.

DSA C

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

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A<=

B>=

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using <= causes out-of-bounds access.

The loop runs from 0 to n-1, so the condition is i < n.

3fill in blank

hard

Fix the error in the XOR operation inside the loop.

DSA C

unique [1] arr[i];

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A^=

B-=

C+=

D*=

Attempts:

3 left

💡 Hint

Common Mistakes

Using + or - instead of XOR.

XOR assignment operator ^= is used to combine bits.

4fill in blank

hard

Fill both blanks to complete the function signature and return statement.

DSA C

int findUnique(int [1][], int [2]) {
    int unique = 0;
    for (int i = 0; i < n; i++) {
        unique ^= arr[i];
    }
    return unique;
}

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

Aarr

Barray

Cn

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent variable names causes errors.

The function takes an array named arr and its size n.

5fill in blank

hard

Fill all three blanks to complete the main function that calls findUnique and prints the result.

DSA C

#include <stdio.h>

int findUnique(int arr[], int n);

int main() {
    int arr[] = {2, 3, 5, 4, 5, 3, 4};
    int n = sizeof(arr) / sizeof([1]);
    int unique = findUnique(arr, [2]);
    printf("Unique element is %[3]d\n", unique);
    return 0;
}

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

Aarr[0]

Bn

Cd

Di

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong format specifier or wrong size calculation.

sizeof(arr[0]) gives size of one element, n is passed as array size, and %d is format specifier for int.