881642. Sort and reverse

Sort and Reverse Slug: sort-and-reverse--171030 Difficulty: Basic Id: 881642 Topic Tags: STL

Summary

This problem is about sorting a given array in descending order (from largest to smallest) and then reversing it. The key concepts involved are sorting and reversal, which are fundamental algorithms in computer science.

Detailed Explanation

The problem can be solved by first sorting the array in descending order using the std::sort function from the C++ Standard Template Library (STL). This function sorts the elements of a range in ascending or descending order. After sorting the array, we need to reverse it. We can use the std::reverse function from the STL to achieve this.

Here's a step-by-step breakdown of the solution:

1. Include the necessary header files: #include <algorithm> and #include <iostream>
2. Define an integer array: int arr[] = {5, 3, 8, 4, 2};
3. Sort the array in descending order using std::sort: std::sort(arr, arr + sizeof(arr) / sizeof(arr[0]), std::greater<int>();
4. Reverse the array using std::reverse: std::reverse(arr, arr + sizeof(arr) / sizeof(arr[0]));

Time complexity: O(n log n), where n is the size of the array. Space complexity: O(1), as we are not using any additional space.

Optimized Solutions

Java

import java.util.Arrays;

public class SortAndReverse {
    public static void main(String[] args) {
        int[] arr = {5, 3, 8, 4, 2};
        Arrays.sort(arr);
        for (int i = 0; i < arr.length / 2; i++) {
            int temp = arr[i];
            arr[i] = arr[arr.length - 1 - i];
            arr[arr.length - 1 - i] = temp;
        }
    }
}

Python

def sort_and_reverse(arr):
    arr.sort(reverse=True)
    return arr[::-1]

arr = [5, 3, 8, 4, 2]
print(sort_and_reverse(arr))

C++

#include <algorithm>
#include <iostream>

void sortAndReverse(int arr[], int n) {
    std::sort(arr, arr + n);
    for (int i = 0; i < n / 2; i++) {
        int temp = arr[i];
        arr[i] = arr[n - 1 - i];
        arr[n - 1 - i] = temp;
    }
}

int main() {
    int arr[] = {5, 3, 8, 4, 2};
    int n = sizeof(arr) / sizeof(arr[0]);
    sortAndReverse(arr, n);
    for (int i = 0; i < n; i++) {
        std::cout << arr[i] << " ";
    }
    return 0;
}

JavaScript

function sortAndReverse(arr) {
    arr.sort((a, b) => b - a);
    return arr.reverse();
}

let arr = [5, 3, 8, 4, 2];
console.log(sortAndReverse(arr));