Skip to content
Related Articles

Related Articles

Improve Article

Program to find if two numbers and their AM and HM are present in an array using STL

  • Last Updated : 26 May, 2021
Geek Week

Given an array of Number and two values A and B, The task is to check the following Conditions:

  1. If two numbers are present in the array or not.
  2. If Yes, then their Arithmetic Mean and Harmonic Mean are also present in the same array or not.
  3. If all conditions are satisfied, Print the Geometric Mean of the two numbers.

The respective means of the numbers can be formulated as follows:
 

Examples:

Input: arr[] = {1.0, 2.0, 2.5, 3.0, 4.0, 4.5, 5.0, 6.0}, A = 3, B = 6. 
Output : GM = 4.24 
Explanation: 
A = 3, B = 6 are present in the array. 
AM = 4.5, HM = 4 are also present in the array. 
So, GM = 4.24
Input: arr = {1.0, 2.0, 2.5, 3.0, 4.0, 4.5, 5.0, 6.0}, A = 4, B = 6. 
Output: AM and HM not found



Approach:

  • The idea is to use Hashing, using which we can simply store the array elements in a Hash container and use constant time O(1) operations to find and track the numbers and their means. Finally, the Geometric Mean is computed if all the conditions are satisfied by observing the simple relation AM * HM = GM2.
  • A step-wise implementation of the above approach is as follows:
    1. A Hash container is defined to store the array elements.
    2. The arithmetic and harmonic means are calculated based on the formulae.
    3. Simple conditional statements are used to find the elements in the Hash container in constant time.
    4. Provided, all conditions are satisfied, the GM is calculated from above relation.

Below is the implementation of the above approach:

C++




// C++ program to check if two numbers
// are present in an array then their
// AM and HM are also present. Finally,
// find the GM of the numbers
#include <bits/stdc++.h>
using namespace std;
 
// Function to find the Arithmetic Mean
// of 2 numbers
float ArithmeticMean(float A, float B)
{
    return (A + B) / 2;
}
 
// Function to find the Harmonic Mean
// of 2 numbers
float HarmonicMean(float A, float B)
{
    return (2 * A * B) / (A + B);
}
 
// Following function checks and computes the
// desired results based on the means
void CheckArithmeticHarmonic(float arr[],
                             float A,
                             float B, int N)
{
     
    // Calculate means
    float AM = ArithmeticMean(A, B);
    float HM = HarmonicMean(A, B);
 
    // Hash container (Set) to store elements
    unordered_set<float> Hash;
 
    // Insertion of array elements in the Set
    for (int i = 0; i < N; i++)
    {
        Hash.insert(arr[i]);
    }
 
    // Conditionals to check if numbers
    // are present in array by Hashing
    if (Hash.find(A) != Hash.end()
        && Hash.find(B) != Hash.end()) {
 
        // Conditionals to check if the AM and HM
        // of the numbers are present in array
        if (Hash.find(AM) != Hash.end()
            && Hash.find(HM) != Hash.end()) {
           
            // If all conditions are satisfied,
            // the Geometric Mean is calculated
            cout << "GM = ";
            printf("%0.2f", sqrt(AM * HM));
        }
        else
        {
            // If numbers are found but the
            // respective AM and HM are not
            // found in the array
            cout << "AM and HM not found";
        }
    }
    else
    {
        // If none of the conditions are satisfied
        cout << "Numbers not found";
    }
}
 
int main()
{
   
    float arr[] = {1.0, 2.0, 2.5, 3.0, 4.0,
                   4.5, 5.0, 6.0};
 
    int N = sizeof(arr)/sizeof(arr[0]);
    float A = 3.0;
    float B = 6.0;
    CheckArithmeticHarmonic(arr, A, B, N);
    return 0;
}

Java




// Java program to check if two numbers
// are present in an array then their
// AM and HM are also present. Finally,
// find the GM of the numbers
import java.util.*;
 
class GFG{
     
// Function to find the Arithmetic Mean
// of 2 numbers
static Double ArithmeticMean(Double A, Double B)
{
    return (A + B) / 2;
}
 
// Function to find the Harmonic Mean
// of 2 numbers
static Double HarmonicMean(Double A, Double B)
{
    return (2 * A * B) / (A + B);
}
 
// Following function checks and computes the
// desired results based on the means
static void CheckArithmeticHarmonic(Double arr[],
                                    Double A,
                                    Double B, int N)
{
 
    // Calculate means
    Double AM = ArithmeticMean(A, B);
    Double HM = HarmonicMean(A, B);
     
    // Hash container (HashMap) to store elements
    HashMap<Double,
            Integer> Hash = new HashMap<Double,
                                        Integer>();
     
    // Insertion of array elements in the Set
    for(int i = 0; i < N; i++)
    {
        Hash.put(arr[i], 1);
    }
     
    // Conditionals to check if numbers
    // are present in array by Hashing
    if (Hash.get(A) != 0 &&
        Hash.get(B) != 0)
    {
         
        // Conditionals to check if the AM and HM
        // of the numbers are present in array
        if (Hash.get(AM) != 0 &&
            Hash.get(HM) != 0)
        {
             
            // If all conditions are satisfied,
            // the Geometric Mean is calculated
            System.out.print("GM = ");
            System.out.format("%.2f", Math.sqrt(AM * HM));
        }
        else
        {
             
            // If numbers are found but the
            // respective AM and HM are not
            // found in the array
            System.out.print("AM and HM not found");
        }
    }
    else
    {
         
        // If none of the conditions are satisfied
        System.out.print("numbers not found");
    }
}
 
// Driver code
public static void main(String args[])
{
    Double arr[] = { 1.0, 2.0, 2.5, 3.0,
                     4.0, 4.5, 5.0, 6.0};
                      
    int N = (arr.length);
    Double A = 3.0;
    Double B = 6.0;
     
    CheckArithmeticHarmonic(arr, A, B, N);
}
}
 
// This code is contributed by Stream_Cipher   

Python3




# Python3 program to check if two numbers
# are present in an array then their
# AM and HM are also present. Finally,
# find the GM of the numbers
from math import sqrt
 
# Function to find the arithmetic mean
# of 2 numbers
def ArithmeticMean(A, B):
    return (A + B) / 2
 
# Function to find the harmonic mean
# of 2 numbers
def HarmonicMean(A, B):
    return (2 * A * B) / (A + B)
 
# Following function checks and computes the
# desired results based on the means
def CheckArithmeticHarmonic(arr, A, B, N):
     
    # Calculate means
    AM = ArithmeticMean(A, B)
    HM = HarmonicMean(A, B)
 
    # Hash container (set) to store elements
    Hash = set()
 
    # Insertion of array elements in the set
    for i in range(N):
        Hash.add(arr[i])
 
    # Conditionals to check if numbers
    # are present in array by Hashing
    if (A in Hash and B in Hash):
         
        # Conditionals to check if the AM and HM
        # of the numbers are present in array
        if (AM in Hash and HM in Hash):
             
            # If all conditions are satisfied,
            # the Geometric Mean is calculated
            print("GM =", round(sqrt(AM * HM), 2))
        else:
             
            # If numbers are found but the
            # respective AM and HM are not
            # found in the array
            print("AM and HM not found")
    else:
         
        # If none of the conditions are satisfied
        print("Numbers not found")
 
# Driver Code
if __name__ == '__main__':
 
    arr = [ 1.0, 2.0, 2.5, 3.0,
            4.0, 4.5, 5.0, 6.0 ]
    N = len(arr)
    A = 3.0
    B = 6.0
     
    CheckArithmeticHarmonic(arr, A, B, N)
 
# This code is contributed by Samarth

C#




// C# program to check if two numbers
// are present in an array then their
// AM and HM are also present. Finally,
// find the GM of the numbers
using System;
using System.Collections.Generic;
 
class GFG{
     
// Function to find the Arithmetic Mean
// of 2 numbers
static Double ArithmeticMean(Double A, Double B)
{
    return (A + B) / 2;
}
 
// Function to find the Harmonic Mean
// of 2 numbers
static Double HarmonicMean(Double A, Double B)
{
    return (2 * A * B) / (A + B);
}
 
// Following function checks and computes the
// desired results based on the means
static void CheckArithmeticHarmonic(Double []arr,
                                    Double A,
                                    Double B, int N)
{
 
    // Calculate means
    Double AM = ArithmeticMean(A, B);
    Double HM = HarmonicMean(A, B);
     
    // Hash container (Set) to store elements
    // HashMap<Double,int> Hash = new HashMap<Double,int>();
    Dictionary<Double,
               int> Hash = new Dictionary<Double,
                                          int>();
     
    // Insertion of array elements in the Set
    for(int i = 0; i < N; i++)
    {
        Hash[arr[i]] = 1;
    }
     
    // Conditionals to check if numbers
    // are present in array by Hashing
    if (Hash.ContainsKey(A) &&
        Hash.ContainsKey(B))
    {
         
        // Conditionals to check if the AM and HM
        // of the numbers are present in array
        if (Hash.ContainsKey(AM) &&
            Hash.ContainsKey(HM))
        {
             
            // If all conditions are satisfied,
            // the Geometric Mean is calculated
            Console.Write("GM = ");
            Console.Write(Math.Round(
                          Math.Sqrt(AM * HM), 2));
        }
        else
        {
             
            // If numbers are found but the
            // respective AM and HM are not
            // found in the array
            Console.WriteLine("AM and HM not found");
        }
    }
    else
    {
         
        // If none of the conditions are satisfied
        Console.WriteLine("numbers not found");
    }
}
 
// Driver code
public static void Main()
{
    Double []arr = { 1.0, 2.0, 2.5, 3.0,
                     4.0, 4.5, 5.0, 6.0 };
 
    int N = (arr.Length);
    Double A = 3.0;
    Double B = 6.0;
     
    CheckArithmeticHarmonic(arr, A, B, N);
}
}
 
// This code is contributed by Stream_Cipher   

Javascript




<script>
 
// Javascript program to check if two numbers
// are present in an array then their
// AM and HM are also present. Finally,
// find the GM of the numbers
 
// Function to find the Arithmetic Mean
// of 2 numbers
function ArithmeticMean(A, B)
{
    return ((A + B) / 2);
}
   
// Function to find the Harmonic Mean
// of 2 numbers
function HarmonicMean(A, B)
{
    return (2 * A * B) / (A + B);
}
   
// Following function checks and computes the
// desired results based on the means
function CheckArithmeticHarmonic(arr, A, B, N)
{
   
    // Calculate means
    let AM = ArithmeticMean(A, B);
    let HM = HarmonicMean(A, B);
       
    // Hash container (HashMap) to store elements
    let Hash = new Map();
       
    // Insertion of array elements in the Set
    for(let i = 0; i < N; i++)
    {
        Hash.set(arr[i], 1);
    }
       
    // Conditionals to check if numbers
    // are present in array by Hashing
    if (Hash.get(A) != 0 &&
        Hash.get(B) != 0)
    {
           
        // Conditionals to check if the AM and HM
        // of the numbers are present in array
        if (Hash.get(AM) != 0 &&
            Hash.get(HM) != 0)
        {
               
            // If all conditions are satisfied,
            // the Geometric Mean is calculated
            document.write("GM = ");
            document.write(Math.sqrt(AM * HM).toFixed(2));
        }
        else
        {
               
            // If numbers are found but the
            // respective AM and HM are not
            // found in the array
            document.write("AM and HM not found");
        }
    }
    else
    {
           
        // If none of the conditions are satisfied
        document.write("numbers not found");
    }
}
 
// Driver code
     
    let arr = [ 1.0, 2.0, 2.5, 3.0,
                     4.0, 4.5, 5.0, 6.0];
                        
    let N = (arr.length);
    let A = 3.0;
    let B = 6.0;
       
    CheckArithmeticHarmonic(arr, A, B, N);
      
     // This code is contributed by code_hunt.
</script>
Output: 
GM = 4.24

Complexity Analysis: 
The overall time complexity of the above program is based on the initial iteration of the array elements at user-defined input. The find operations associated with the Set are all O(1) constant-time operations. Therefore, the complexity of the program is O(N) where N is the size of the array.
 

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.




My Personal Notes arrow_drop_up
Recommended Articles
Page :