Question

Write a C++ program to find the kth largest number among N numbers. You may assume 0 < k <= N. The numbers are in an input file. Input value of k from the user. Read the first k numbers into an array and sort them into non-increasing order. Next, read the remaining numbers one by one (until end-of-file). As a new number is read, if it is smaller than the number in position k-1 in the array, it is ignored. Otherwise, it is placed in its correct position in the array, bumping out the number in position k-1. When all numbers are read, the number in position k-1 is the answer.

Answer 1

Explanation::

• Code in C++ is given below
• OUTPUT is given at the end of the code

CODE in C++::

#include <iostream>

#include <fstream>

using namespace std;

void sort(int arr[],int k);

int main() {

  /**

  * We will scan numbers from a file named input.txt

  * In input.txt file, numbers are stored as

  * one number per line

  */

  ifstream infile("input.txt");

  int n,k,i=0;

  cout<<"Enter the value of k : ";

  cin>>k;

  /**

  * Creating array of size k

  */

  int arr[k];

  while(infile>>n){

    if(i<k){

      arr[i]=n;

      i++;

    }else{

      /**

      * Sorting in non-increasing order

      */

      sort(arr,k);

      if(n>=arr[k-1]){

        arr[k-1]=n;

      }

  

    }

  }

  sort(arr,k);

  cout<<"The kth Largest number is "<<arr[k-1]<<endl;

}

void sort(int arr[],int k){

  for(int i = 0; i < k - 1; i++)

    {

        for(int j = 0; j < k - 1 - i; j++)

        {

            if(arr[j] < arr[j + 1])

            {

                int num = arr[j];

                arr[j] = arr[j + 1];

                arr[j + 1] = num;

            }

        }

    }

}

input.txt ::

12

4

5

6

7

3

4

5

6

67

78

OUTPUT:

Enter the value of k : 5

The kth Largest number is 6

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