Example: Sorting-Based Duplicate Finder in C++

// Sorting-Based Duplicate Finder
    #include <iostream>
    #include <vector>
    #include <algorithm> // For std::sort

    int findDuplicateSorting(std::vector<int>& nums) {
        // Step 1: Sort the array
        std::sort(nums.begin(), nums.end());

        // Step 2: Iterate through the sorted array and check adjacent elements
        for (size_t i = 0; i < nums.size() - 1; ++i) {
            // Step 3: If an element is equal to its successor, it's a duplicate
            if (nums[i] == nums[i+1]) {
                return nums[i];
            }
        }
        // Step 4: If no duplicate found
        return -1;
    }

    int main() {
        std::vector<int> nums = {1, 3, 4, 2, 2};
        int duplicate = findDuplicateSorting(nums);

        if (duplicate != -1) {
            std::cout << "The duplicate number is: " << duplicate << std::endl;
        } else {
            std::cout << "No duplicate found." << std::endl;
        }

        std::vector<int> nums2 = {3, 1, 3, 4, 2};
        duplicate = findDuplicateSorting(nums2);
        if (duplicate != -1) {
            std::cout << "The duplicate number is: " << duplicate << std::endl;
        } else {
            std::cout << "No duplicate found." << std.endl;
        }

        return 0;
    }