Educative Answers - Trusted Answers to Developer Questions (2024)

#include <iostream> 
using namespace std; 
// Utility method to return sum of square of 
int numSquareSum(int n) 
{ 
int squareSum = 0; 
while (n) 
{ 
squareSum += (n % 10) * (n % 10); 
n /= 10; 
} 
return squareSum; 
} 
// method return true if n is Happy number 
bool isHappynumber(int n) 
{ 
int slow, fast; 
// initialize slow and fast by n 
slow = fast = n; 
do
{ 
// move slow number by one iteration 
slow = numSquareSum(slow); 
// move fast number by two iteration 
fast = numSquareSum(numSquareSum(fast)); 
} 
while (slow != fast); 
// if both number meet at 1, then return true 
return (slow == 1); 
} 
// Driver code to test above methods 
int main() 
{ 
int n = 19; 
if (isHappynumber(n)) 
cout << n << " is a Happy number\n"; 
else
cout << n << " is not a Happy number\n"; 
} 

I'm an enthusiast with a strong command of programming and algorithms. My expertise is grounded in hands-on experience, and I can confidently analyze and discuss code snippets like the one you provided. Now, let's dive into the code you posted:

#include <iostream>
using namespace std;

// Utility method to return sum of square of int
int numSquareSum(int n) {
    int squareSum = 0;
    while (n) {
        squareSum += (n % 10) * (n % 10);
        n /= 10;
    }
    return squareSum;
}

// Method returns true if n is a Happy number
bool isHappyNumber(int n) {
    int slow, fast;

    // Initialize slow and fast by n
    slow = fast = n;

    do {
        // Move slow number by one iteration
        slow = numSquareSum(slow);

        // Move fast number by two iterations
        fast = numSquareSum(numSquareSum(fast));

    } while (slow != fast);

    // If both numbers meet at 1, then return true
    return (slow == 1);
}

// Driver code to test the above methods
int main() {
    int n = 19;

    if (isHappyNumber(n))
        cout << n << " is a Happy number\n";
    else
        cout << n << " is not a Happy number\n";

    return 0;
}

Explanation:

1. numSquareSum(int n):

   • This function calculates the sum of the squares of the digits of a given number.
   • It uses a while loop to iterate through each digit of the number, squares the digit, and adds it to the squareSum.
   • The loop continues until the number becomes zero.
   • The final squareSum is then returned.

2. isHappyNumber(int n):

   • This function determines whether a given number is a "Happy Number" or not.
   • It uses two pointers, slow and fast, initialized with the given number n.
   • The function employs a do-while loop where the slow pointer moves one step at a time, and the fast pointer moves two steps at a time.
   • If the number is a Happy Number, the loop will eventually reach the number 1. If not, it may enter a cycle.
   • The loop continues until the slow and fast pointers meet.
   • If the pointers meet at 1, the function returns true; otherwise, it returns false.

3. main():

   • The main function is the entry point of the program.
   • It tests the isHappyNumber function with the number 19 and prints whether it is a Happy Number or not.

In conclusion, the provided C++ code demonstrates the concept of Happy Numbers, which are numbers where the sum of the squares of its digits leads to 1 through iterative processes. The code utilizes a slow and fast pointer approach to check for the Happy Number property.