Two Non Repeating Elements in Array Using XOR in DSA C - Build from Scratch

Two Non Repeating Elements in Array Using XOR

📖 Scenario: Imagine you have a list of numbers where every number appears twice except for two unique numbers that appear only once. You want to find those two unique numbers efficiently.

🎯 Goal: Build a program that finds the two numbers that appear only once in an array where all other numbers appear twice, using the XOR operation.

📋 What You'll Learn

Create an integer array called arr with the exact values: 2, 4, 7, 9, 2, 4

Create an integer variable called xor_all and initialize it to 0

Use a for loop with variable i to XOR all elements of arr into xor_all

Print the two unique numbers separated by a space

💡 Why This Matters

🌍 Real World

Finding unique items in data streams or logs where duplicates are common.

💼 Career

Bitwise operations and efficient algorithms are important in embedded systems, security, and performance-critical applications.

1

Create the array with given values

Create an integer array called arr with the exact values: 2, 4, 7, 9, 2, 4.

DSA C

# Create the array 'arr' with the given values
// Your code here

Hint

Use int arr[] = {2, 4, 7, 9, 2, 4}; to create the array and int n = 6; for its size.

2

Initialize XOR variable

Create an integer variable called xor_all and initialize it to 0.

DSA C

int arr[] = {2, 4, 7, 9, 2, 4};
int n = 6;
// Create 'xor_all' variable and set it to 0
// Your code here

Hint

Use int xor_all = 0; to start XOR accumulation.

3

XOR all elements in the array

Use a for loop with variable i from 0 to n - 1 to XOR each element of arr into xor_all.

DSA C

int arr[] = {2, 4, 7, 9, 2, 4};
int n = 6;
int xor_all = 0;
// XOR all elements of arr into xor_all
// Your code here

Hint

Use for (int i = 0; i < n; i++) { xor_all ^= arr[i]; } to XOR all elements.

4

Find and print the two unique numbers

Complete the program to find the two unique numbers using XOR logic and print them separated by a space.

DSA C

int arr[] = {2, 4, 7, 9, 2, 4};
int n = 6;
int xor_all = 0;
for (int i = 0; i < n; i++) {
    xor_all ^= arr[i];
}
// Find rightmost set bit in xor_all
// Separate elements into two groups and XOR
// Print the two unique numbers
// Your code here

Hint

Use the rightmost set bit of xor_all to divide elements into two groups. XOR each group separately to find the unique numbers. Then print them.