C++ Exercises: Check whether a given positive integer is a perfect square or not

Last update on December 20 2024 12:30:30 (UTC/GMT +8 hours)

Write a C++ program to check whether a given positive integer is a perfect square or not.
In mathematics, a square number or perfect square is an integer that is the square of an integer, in other words, it is the product of some integer with itself. For example, 9 is a square number, since it can be written as 3 × 3.

Sample Input: n = 1
Is 1 is perfect number? 1
Sample Input: n = 13
Is 13 is perfect number? 0

Sample Solution:

C++ Code :

#include <iostream>
#include <cmath>

using namespace std;

// Function to check if 'num' is a perfect square
bool is_Perfect_Square(int num) {
    // Initialize start and end numbers for binary search
    long long start_num = 0;
    long long end_num = num;

    // Binary search to find the perfect square
    while(start_num + 1 < end_num) {
        long long mid_num = start_num + (end_num - start_num) / 2;
        if (mid_num * mid_num < num) {
            start_num = mid_num; // If square of mid_num is less than 'num', update the start_num
        } else if(mid_num * mid_num > num) {
            end_num = mid_num; // If square of mid_num is greater than 'num', update the end_num
        } else {
            return true; // If mid_num is a perfect square, return true
        }
    }

    // Check if start_num or end_num square is equal to 'num'
    return start_num * start_num == num || end_num * end_num == num;
}

int main() 
{
    int n = 1;
    // Check if 'n' is a perfect square
    cout << "\nIs "<< n << " is perfect number? " << is_Perfect_Square(n) << endl;   
    n = 13;
    // Check if 'n' is a perfect square
    cout << "\nIs "<< n << " is perfect number? " << is_Perfect_Square(n) << endl; 
    n = 16;
    // Check if 'n' is a perfect square
    cout << "\nIs "<< n << " is perfect number? " << is_Perfect_Square(n) << endl; 
    n = 125;
    // Check if 'n' is a perfect square
    cout << "\nIs "<< n << " is perfect number? " << is_Perfect_Square(n) << endl;    
    return 0;    
}

Sample Output:

Is 1 is perfect number? 1

Is 13 is perfect number? 0

Is 16 is perfect number? 1

Is 125 is perfect number? 0

Flowchart:

C++ Code Editor:

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