3rdmax.cpp

#include <iostream>
using namespace std;

int thirdMaximum(int* arr, int size) {
    if (size < 3) {
        cout << "Array must have at least 3 elements!" << endl;
        return -1; // Indicate error
    }

    // Initialize the first, second, and third maximum to "very small" values
    int firstMax = arr[0], secondMax = arr[0], thirdMax = arr[0];

    // Ensure the initial values differ
    for (int i = 1; i < size; ++i) {
        if (arr[i] < firstMax) {
            thirdMax = secondMax = firstMax = arr[i];
            break;
        }
    }

    for (int i = 0; i < size; ++i) {
        int current = arr[i];

        // Update the three maximums
        if (current > firstMax) {
            thirdMax = secondMax;
            secondMax = firstMax;
            firstMax = current;
        } else if (current > secondMax && current < firstMax) {
            thirdMax = secondMax;
            secondMax = current;
        } else if (current > thirdMax && current < secondMax) {
            thirdMax = current;
        }
    }

    return thirdMax;
}

int main() {
    int n;
    cout << "Enter the size of the array: ";
    cin >> n;

    if (n < 3) {
        cout << "Array size must be at least 3." << endl;
        return 1;
    }

    // Dynamically allocate memory for the array
    int* arr = new int[n];

    cout << "Enter the elements of the array:\n";
    for (int i = 0; i < n; ++i) {
        cin >> arr[i];
    }

    int thirdMax = thirdMaximum(arr, n);
    cout << "The third maximum value is: " << thirdMax << endl;

    // Free the allocated memory
    delete[] arr;

    return 0;
}