# Program to print the series 2, 1, 4, 3, 6, 5, …. up to N terms

Given a number N, the task is to print the below pattern upto N terms:

2, 1, 4, 3, 6, 5, …. N terms

Examples:

```Input: N = 4
Output: 2, 1, 4, 3

Explanation:
Nth Term = (N % 2 == 0) ? (N - 1) : (N + 1)
1st term = (1 % 2 == 0) ? (1 - 1) : (1 + 1)
= (1 + 1)
= 2
2nd term = (2 % 2 == 0) ? (2 - 1) : (2 + 1)
= (2 - 1)
= 1
3rd term = (3 % 2 == 0) ? (3 - 1) : (3 + 1)
= (3 + 1)
= 4
4th term = (4 % 2 == 0) ? (4 - 1) : (4 + 1)
= (4 - 1)
= 3
Therefore, Series = 2, 1, 4, 3

Input: N = 7
Output: 2, 1, 4, 3, 6, 5, 8
```

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

Formula:

```Nth Term = (N % 2 == 0) ? (N - 1) : (N + 1)
```

Below is the solution to above problem:

## C++

 `// C++ program to print the series  ` `// 2, 1, 4, 3, 6, 5, …. up to N terms ` `#include ` `using` `namespace` `std; ` ` `  `// Function to print the series ` `void` `printPattern(``int` `N) ` `{ ` ` `  `    ``for` `(``int` `i = 1; i <= N; i++) { ` ` `  `        ``// Find and print the ith term ` `        ``cout <<``" "``<<((i % 2 == 0) ? (i - 1) : (i + 1)); ` `    ``} ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` ` `  `    ``// Get the value of N ` `    ``int` `N = 10; ` ` `  `    ``// Print the Series ` `    ``printPattern(N); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java Program to print the series  ` `// 2, 1, 4, 3, 6, 5, …. up to N terms  ` ` `  `import` `java.util.*; ` `import` `java.lang.*; ` `import` `java.io.*; ` ` `  `class` `GFG ` `{ ` `// Function to print the series  ` `static` `void` `printPattern(``int` `N)  ` `{  ` `   `  `    ``for` `(``int` `i = ``1``; i <= N; i++) {  ` `   `  `        ``// Find and print the ith term  ` `        ``System.out.print(``" "``+((i % ``2` `== ``0``) ? (i - ``1``) : (i + ``1``)));  ` `    ``}  ` `}  ` `   `  `// Driver code  ` `public` `static` `void` `main(String args[])  ` `{  ` `   `  `    ``// Get the value of N  ` `    ``int` `N = ``10``;  ` `   `  `    ``// Print the Series  ` `    ``printPattern(N);  ` `   `  `} ` `}  `

## Python3

 `# Python program to print the series  ` `# 2, 1, 4, 3, 6, 5, …. up to N terms  ` ` `  `# Function to print the series  ` `def` `printPattern(N): ` `    ``for` `i ``in` `range``(``1``, N ``+` `1``): ` `         `  `        ``# Find and print the ith term  ` `        ``print``(i ``-` `1` `if` `i ``%` `2` `=``=` `0`  `                    ``else` `i ``+` `1``, end ``=` `" "``) ` ` `  `# Driver code ` `N ``=` `10` `printPattern(N) ` ` `  `# This code is contributed by Shrikant13 `

## C#

 `// C# program to print the series  ` `// 2, 1, 4, 3, 6, 5, …. up to N terms ` `using` `System; ` ` `  `class` `GFG ` `{ ` `// Function to print the series ` `public` `void` `printPattern(``int` `N) ` `{ ` ` `  `    ``for` `(``int` `i = 1; i <= N; i++) ` `    ``{ ` ` `  `        ``// Find and print the ith term ` `        ``int` `a = ((i % 2 == 0) ?  ` `                      ``(i - 1) : (i + 1)); ` `        ``Console.Write(``" {0}"``, a); ` `    ``} ` `} ` ` `  `// Driver code ` `public` `static` `void` `Main() ` `{ ` `    ``GFG g = ``new` `GFG(); ` `     `  `    ``// Get the value of N ` `    ``int` `N = 10; ` ` `  `    ``// Print the Series ` `    ``g.printPattern(N); ` `} ` `} ` ` `  `// This code is contributed ` `// by Soumik `

## PHP

 ` `

Output:

```2 1 4 3 6 5 8 7 10 9
```

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