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Find k maximum elements of array in original order

  • Difficulty Level : Easy

Given an array arr[] and an integer k, we need to print k maximum elements of given array. The elements should printed in the order of the input.
Note : k is always less than or equal to n.

Examples:  

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Input : arr[] = {10 50 30 60 15}
        k = 2
Output : 50 60
The top 2 elements are printed
as per their appearance in original
array.

Input : arr[] = {50 8 45 12 25 40 84}
            k = 3
Output : 50 45 84

Method 1: We search for the maximum element k times in the given array. Each time we find one maximum element, we print it and replace it with minus infinite (INT_MIN in C) in the array. The time complexity of this method is O(n*k).



Method 2: In this method, we store the original array in a new array and will sort the new array in descending order. After sorting, we iterate the original array from 0 to n and print all those elements that appear in first k elements of new array. For searching, we can do Binary Search.

C++




// C++ program to find k maximum elements
// of array in original order
#include <bits/stdc++.h>
using namespace std;
 
// Function to print m Maximum elements
void printMax(int arr[], int k, int n)
{
    // vector to store the copy of the
    // original array
    vector<int> brr(arr, arr + n);
 
    // Sorting the vector in descending
    // order. Please refer below link for
    // details
    sort(brr.begin(), brr.end(), greater<int>());
 
    // Traversing through original array and
    // printing all those elements that are
    // in first k of sorted vector.
    // Please refer https://goo.gl/44Rwgt
    // for details of binary_search()
    for (int i = 0; i < n; ++i)
        if (binary_search(brr.begin(),
                 brr.begin() + k, arr[i],
                        greater<int>()))
            cout << arr[i] << " ";
}
 
// Driver code
int main()
{
    int arr[] = { 50, 8, 45, 12, 25, 40, 84 };
    int n = sizeof(arr) / sizeof(arr[0]);
    int k = 3;
    printMax(arr, k, n);
    return 0;
}

Java




// Java program to find k maximum 
// elements of array in original order
import java.util.Arrays;
import java.util.Collections;
 
public class GfG {
     
    // Function to print m Maximum elements
    public static void printMax(int arr[], int k, int n)
    {
        // Array to store the copy
        // of the original array
        Integer[] brr = new Integer[n];
         
        for (int i = 0; i < n; i++)
        brr[i] = arr[i];
         
        // Sorting the array in
        // descending order
        Arrays.sort(brr, Collections.reverseOrder());
     
        // Traversing through original array and
        // printing all those elements that are
        // in first k of sorted array.
        // Please refer https://goo.gl/uj5RCD
        // for details of Arrays.binarySearch()
        for (int i = 0; i < n; ++i)
            if (Arrays.binarySearch(brr, arr[i],
                    Collections.reverseOrder()) >= 0
                 && Arrays.binarySearch(brr, arr[i],
                    Collections.reverseOrder()) < k)
                     
                System.out.print(arr[i]+ " ");
    }
 
    // Driver code
    public static void main(String args[])
    {
        int arr[] = { 50, 8, 45, 12, 25, 40, 84 };
        int n = arr.length;
        int k = 3;
        printMax(arr, k, n);
    }
}
 
// This code is contributed by Swetank Modi

Python3




# Python3 program to find k maximum elements
# of array in original order
 
# Function to pr m Maximum elements
def printMax(arr, k, n):
     
    # vector to store the copy of the
    # original array
    brr = arr.copy()
     
    # Sorting the vector in descending
    # order. Please refer below link for
    # details
    brr.sort(reverse = True)
     
    # Traversing through original array and
    # pring all those elements that are
    # in first k of sorted vector.
    for i in range(n):
        if (arr[i] in brr[0:k]):
            print(arr[i], end = " ")
 
# Driver code
arr = [ 50, 8, 45, 12, 25, 40, 84 ]
n = len(arr)
k = 3
 
printMax(arr, k, n)
 
# This code is contributed by SHUBHAMSINGH10

C#




// C# program to find k maximum 
// elements of array in original order
using System;
using System.Linq;
 
class GFG{
     
// Function to print m Maximum elements
public static void printMax(int[] arr, int k,
                            int n)
{
     
    // Array to store the copy
    // of the original array
    int[] brr = new int[n];
     
    for(int i = 0; i < n; i++)
        brr[i] = arr[i];
     
    // Sorting the array in
    // descending order
    Array.Sort(brr);
    Array.Reverse(brr);
     
    int[] crr = new int[k];
     
    for(int i = 0; i < k; i++)
    {
        crr[i] = brr[i];
    }
 
    // Traversing through original array and
    // printing all those elements that are
    // in first k of sorted array.
    // Please refer https://goo.gl/uj5RCD
    // for details of Array.BinarySearch()
    for(int i = 0; i < n; ++i)
    {
        if (crr.Contains(arr[i]))
        {
            Console.Write(arr[i] + " ");
        }
    }
}
 
// Driver code
public static void Main()
{
    int[] arr = { 50, 8, 45, 12, 25, 40, 84 };
    int n = arr.Length;
    int k = 3;
     
    printMax(arr, k, n);
}
}
 
// This code is contributed by Shubhamsingh10

Javascript




<script>
 
// JavaScript program to find k maximum elements
// of array in original order
 
// Function to print m Maximum elements
function printMax(arr, k, n)
{
    // vector to store the copy of the
    // original array
    var brr = arr.slice();
 
    // Sorting the vector in descending
    // order. Please refer below link for
    // details
    brr.sort((a, b) => b - a);
     
    // Traversing through original array and
    // printing all those elements that are
    // in first k of sorted vector.
    // Please refer https://goo.gl/44Rwgt
    // for details of binary_search()
    for (var i = 0; i < n; ++i)
        if (brr.indexOf(arr[i]) < k)
            document.write(arr[i] +" ");
}
 
// Driver code
var arr = [ 50, 8, 45, 12, 25, 40, 84 ];
var n = arr.length;
var k = 3;
printMax(arr, k, n);
 
// This code is contributed by ShubhamSingh10
 
</script>

Output: 

50 45 84 

Time Complexity: O(n Log n) for sorting. 
Auxiliary Space: O(n)
 




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