Example: MissingElementsBooleanArray in C++

// MissingElementsBooleanArray
#include <iostream>
#include <vector>
#include <numeric> // For std::iota if needed, though not strictly for this problem
#include <algorithm> // For std::max_element, std::min_element

using namespace std;

// Function to find missing elements using a boolean array
vector<int> findMissingBooleanArray(const vector<int>& arr, int lowerBound, int upperBound) {
    if (lowerBound > upperBound) {
        return {}; // Invalid range
    }

    // Determine the size needed for the boolean array
    // We need indices from lowerBound to upperBound
    // So, size = (upperBound - lowerBound + 1)
    vector<bool> present(upperBound - lowerBound + 1, false);

    // Mark numbers present in the input array
    for (int num : arr) {
        // Only consider numbers within the specified range
        if (num >= lowerBound && num <= upperBound) {
            present[num - lowerBound] = true;
        }
    }

    // Collect missing numbers
    vector<int> missingElements;
    for (int i = 0; i <= upperBound - lowerBound; ++i) {
        if (!present[i]) {
            missingElements.push_back(i + lowerBound);
        }
    }

    return missingElements;
}

int main() {
    // Step 1: Define the input array and the range
    vector<int> numbers = {10, 12, 11, 15, 8, 17};
    int lower = 10;
    int upper = 15;

    cout << "Input array: ";
    for (int num : numbers) {
        cout << num << " ";
    }
    cout << endl;
    cout << "Range: [" << lower << ", " << upper << "]" << endl;

    // Step 2: Call the function to find missing elements
    vector<int> missing = findMissingBooleanArray(numbers, lower, upper);

    // Step 3: Display the results
    cout << "Missing elements in range [" << lower << ", " << upper << "]: ";
    if (missing.empty()) {
        cout << "None";
    } else {
        for (int num : missing) {
            cout << num << " ";
        }
    }
    cout << endl;

    // Example with a different range or array
    vector<int> nums2 = {1, 3, 5};
    int lower2 = 1;
    int upper2 = 5;
    cout << "\nInput array: ";
    for (int num : nums2) {
        cout << num << " ";
    }
    cout << endl;
    cout << "Range: [" << lower2 << ", " << upper2 << "]" << endl;
    vector<int> missing2 = findMissingBooleanArray(nums2, lower2, upper2);
    cout << "Missing elements in range [" << lower2 << ", " << upper2 << "]: ";
    if (missing2.empty()) {
        cout << "None";
    } else {
        for (int num : missing2) {
            cout << num << " ";
        }
    }
    cout << endl;

    return 0;
}