Program to compare m^n and n^m

The problem statement states that we need to write a program to compare m^n and n^m. We need to figure out the algorithm to calculate $m^{n}$ and $n^{m}$ and compare them and print accordingly if $m^{n}$ is greater than $n^{m}$, or if $m^{n}$ is less than $n^{m}$ , or if they both are equal. We will be given two positive numbers, m and n and we need to find out $m^{n}$ and $n^{m}$ and compare both the values.

For example,

INPUT : m=2 , n=5

OUTPUT : m^n is greater than n^m.

Explanation : $m^{n}$ which is 25 = 32 and $n^{m}$ which is 52 = 25. Since 32 is greater than 25, we will print m^n is greater than n^m.

INPUT : m=6 , n=4

OUTPUT : n^m is greater than m^n.

Explanation : $m^{n}$ is 64 which is equal to 1296 and $n^{m}$ is 46 which is equal to 4096. Since 4096 is greater than 1296, we will print n^m is greater than m^n.

Algorithm

The basic approach that comes to mind after seeing the problem or the naive approach to the problem is calculating the values of $m^{n}$ 𝑎𝑛𝑑 $n^{m}$. After calculating the values for both then compare them using the if statement and print accordingly. We can calculate the values of $m^{n}$ 𝑎𝑛𝑑 $n^{m}$ using the pow function in C++.

Syntax

int value= pow(m,n)

The first value passed in the function represents the base and the second value passed represents the power. But this approach can only be used for the smaller values of m and n since calculating values of $m^{n}$ 𝑎𝑛𝑑 $n^{m}$ will cause overflow in int data type for larger values of m and n.

So, the efficient approach to the problem can be using a log function. Let’s explain the approach with an example. For comparing the values of $m^{n}$ 𝑎𝑛𝑑 $n^{m}$, We can use logs on both sides. It can be expressed as −

$$\log_{e}{(m^{n})}\:and\:\log_{e}{(n^{m})}$$

According to the laws of logarithmic function, this can be further written as

$$n\:\times\:\log_{e}{(m)}\:and\:m\:\times\:\log_{e}{(n)}$$

Now calculating these values and then comparing both the values will give us our required output. In C++, there is a built-in function called log which returns the natural log of any value passed through it. The natural log of any value is the logarithmic value with base e of the number.

Syntax

double ans= log(a)

It returns the natural log of a.

Below is the approach to solve the problem using this algorithm.

Approach

The steps that we are going to follow in this approach are −

• Initialize a function where we will calculate and compare both the values.

• Declare two variables.

• Store the calculated values in the declared values.

• Compare the values. If $m^{n}$ is greater than $n^{m}$, then print m^n is greater than n^m. Else if $n^{m}$ is greater than $m^{n}$ then print n^m is greater than m^n or if they are equal then print m^n is equal to n^m.

Example

The implementation of the approach in C++ −

#include <iostream>
#include <bits/stdc++.h>
using namespace std;

//function to calculate and compare both the values
void compare(int m, int n){
   double m_n,n_m; //variables to store the calculated value
   m_n= n * (double)log(m); //type casting value of log into double to store decimal values since m is int data type
   n_m= m * (double)log(n);
   //comparing values using conditional statements and printing accordingly
   if(m_n>n_m){
      cout<<"m^n is greater than n^m"<<endl;
   }
   else if(m_n<n_m){
      cout<<"n^m is greater than m^n"<<endl;
   }
   else
      cout<<"m^n is equal to n^m"<<endl;
}
int main(){
   int m=543,n=248;
   compare(m,n);
   m=10,n=40;
   compare(m,n);
   return 0;
}

Output

n^m is greater than m^n
m^n is greater than n^m

Time Complexity : O(1), constant time is taken.

Space Complexity : O(1), since no extra space is taken.

Conclusion

We discussed the approach to solve the problem to compare m^n and n^m. We use the log function in C++ to compare the values of m^n and n^m and print the answer accordingly.

I hope you find this article helpful and have cleared all your doubts regarding the problem and approach to solve the problem.