C++ Exercises: Find the missing number in a given array of integers taken from the sequence 0, 1, 2, 3, ...,n

C++ Math: Exercise-26 with Solution

Write a C++ program to find the missing number in a given array of integers taken from the sequence 0, 1, 2, 3, ...,n.

Sample Input: arr[10] = {10, 9, 4, 6, 3, 2, 5, 7, 1, 0 }
Sample Output: Missing number in the said array: 8
Sample Input: arr1[4] = {0, 3, 4, 2}
Sample Output: Missing number in the said array: 1

Sample Solution:

C++ Code :

#include <iostream>

using namespace std;

// Function to find the missing number in an array of integers
int missingNumber(int nums[], int arr_size) {
    // Check if the array pointer is NULL or array size is zero
    if (NULL == nums || arr_size == 0) {
        return 0; // Return 0 if the array is empty or NULL
    }

    int result = arr_size; // Initialize result as the size of the array

    // XOR operation to find the missing number
    for (int i = 0; i < arr_size; i++) {
        result ^= i; // XOR operation with index 'i'
        result ^= nums[i]; // XOR operation with the element at index 'i'
    }
    return result; // Return the missing number
}

int main() {
    int arr[10] = {10, 9, 4, 6, 3, 2, 5, 7, 1, 0};
    int arr_size = sizeof(arr) / sizeof(arr[0]);

    cout << "Original array\n";
    // Print the original array in reverse order
    for (int i = arr_size - 1; i >= 0; i--) {
        cout << arr[i] << " ";
    }

    cout << "\nMissing number in the said array: ";
    cout << "\n" << missingNumber(arr, arr_size); // Find and print the missing number in the array

    int arr1[4] = {0, 3, 4, 2};
    arr_size = sizeof(arr1) / sizeof(arr1[0]);

    cout << "\n\nOriginal array\n";
    // Print the original array in reverse order
    for (int i = arr_size - 1; i >= 0; i--) {
        cout << arr1[i] << " ";
    }

    cout << "\nMissing number in the said array: ";
    cout << "\n" << missingNumber(arr1, arr_size); // Find and print the missing number in the second array

    return 0;
}

Sample Output:

Original array
0 1 7 5 2 3 6 4 9 10
Missing number in the said array:
8

Original array
2 4 3 0
Missing number in the said array:
1

Flowchart:

C++ Code Editor:

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