# Check whether a number can be represented as difference of two squares

Given a number N, the task is to check if this number can be represented as the difference of two perfect squares or not.

Examples:

Input: N = 3
Output: Yes
Explanation:
22 – 11 = 3

Input: N = 10
Output: No

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: The idea is that all the numbers can be represented as the difference of two squares except the numbers which yield the remainder of 2 when divided by 4.

Let’s visualize this by taking a few examples:

```N = 4 => 42 - 02
N = 6 => Can't be expressed as 6 % 4 = 2
N = 8 => 32 - 12
N = 10 => Can't be expressed as 10 % 4 = 2
N = 11 => 62 - 52
N = 12 => 42 - 22
and so on...
```

Therefore, the idea is to simply check the remainder for 2 when the given number is divided by 4.

Below is the implementation of the above approach:

 `// C++ program to check whether a number ` `// can be represented by the difference ` `// of two squares ` ` `  `#include ` `using` `namespace` `std; ` ` `  `// Function to check whether a number ` `// can be represented by the difference ` `// of two squares ` `bool` `difSquare(``int` `n) ` `{ ` `    ``// Checking if n % 4 = 2 or not ` `    ``if` `(n % 4 != 2) { ` `        ``return` `true``; ` `    ``} ` ` `  `    ``return` `false``; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` ` `  `    ``int` `n = 45; ` `    ``if` `(difSquare(n)) { ` `        ``cout << ``"Yes\n"``; ` `    ``} ` `    ``else` `{ ` `        ``cout << ``"No\n"``; ` `    ``} ` `    ``return` `0; ` `} `

Output:

```Yes
```

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