# Find if a molecule can be formed from 3 atoms using their valence numbers

Valence number of an atom is defined as the exact number of bonds the atom must form with other atoms. Given valence number of 3 atoms, the task is to determine if they can form a molecule together or not. Atoms can form multiple bonds with each other.

Examples:

```Input: 2 4 2
Output: YES
The bonds are between the following atoms:
1 - 2
1 - 2
2 - 3
2 - 3

Input: 1 2 3
Output: NO
```

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

Approach: Let the valence numbers be a, b and c. Let c be the largest. We have 2 cases in which the molecule cannot be formed:

• a+b+c is odd: Since every bond decreases the valence number of 2 atoms by 1, the sum of valence numbers should be an even number.
• a+b < c: In this case, c will be left unsatisfied even if every bond is formed with it.

Below is the implementation of the above approach:

## C++

 `// C++ implementation of the above approach ` `#include ` `using` `namespace` `std; ` ` `  `// Function to check if it is possible ` `void` `printPossible(``int` `a, ``int` `b, ``int` `c) ` `{ ` `    ``if` `((a + b + c) % 2 != 0 || a + b < c) ` `        ``cout << ``"NO"``; ` `    ``else` `        ``cout << ``"YES"``; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``int` `a = 2, b = 4, c = 2; ` `    ``printPossible(a, b, c); ` ` `  `  ``return` `0; ` `} `

## Java

 `// Java implementation of the above approach  ` ` `  `import` `java.io.*; ` ` `  `class` `GFG { ` `    ``// Function to check if it is possible  ` `static` `void` `printPossible(``int` `a, ``int` `b, ``int` `c)  ` `{  ` `    ``if` `((a + b + c) % ``2` `!= ``0` `|| a + b < c)  ` `        ``System.out.println(``"NO"``);  ` `    ``else` `        ``System.out.println(``"YES"``);  ` `}  ` ` `  `// Driver code  ` `    ``public` `static` `void` `main (String[] args) { ` ` `  `    ``int` `a = ``2``, b = ``4``, c = ``2``;  ` `    ``printPossible(a, b, c);  ` `    ``}  ` `}  ` ` `  `// This code is contributed by akt_mit `

## Python3

 `# Python 3 implementation of the ` `# above approach  ` ` `  `# Function to check if it is possible  ` `def` `printPossible( a, b, c): ` ` `  `    ``if` `((a ``+` `b ``+` `c) ``%` `2` `!``=` `0` `or` `a ``+` `b < c): ` `        ``print` `(``"NO"``) ` `    ``else``: ` `        ``print` `(``"YES"``) ` ` `  `# Driver code  ` `if` `__name__ ``=``=` `"__main__"``: ` ` `  `    ``a ``=` `2` `    ``b ``=` `4` `    ``c ``=` `2` `    ``printPossible(a, b, c) ` ` `  `# This code is contributed  ` `# by ChitraNayal `

## C#

 `// C# implementation of the above approach ` `using` `System; ` ` `  `class` `GFG ` `{ ` ` `  `// Function to check if it is possible ` `static` `void` `printPossible(``int` `a, ``int` `b, ``int` `c) ` `{ ` `    ``if` `((a + b + c) % 2 != 0 || a + b < c) ` `        ``Console.Write(``"NO"``); ` `    ``else` `        ``Console.Write(``"YES"``); ` `} ` ` `  `// Driver code ` `public` `static` `void` `Main() ` `{ ` `    ``int` `a = 2, b = 4, c = 2; ` `    ``printPossible(a, b, c); ` `} ` `} ` ` `  `// This code is contributed ` `// by Akanksha Rai `

## PHP

 ` `

Output:

`Yes`

Time complexity: O(1)

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