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# Print the following pyramid pattern

Given a positive integer n. The problem is to print the pyramid pattern as described in the examples below.

Examples:

```Input : n = 4
Output :
1
3*2
4*5*6
10*9*8*7

Input : n = 5
Output :
1
3*2
4*5*6
10*9*8*7
11*12*13*14*15```

Approach: For odd number row, values are being displayed in increasing order and for even number row, values are being displayed in decreasing order. The only other trick is to how to iterate the loops.

Algorithm:

```printPattern(int n)
Declare j, k
Initialize k = 0

for i = 1 to n

if i%2 != 0
for j = k+1, j < k+i, j++
print j and "*"
print j and new line
k = ++j

else
k = k+i-1
for j = k, j > k-i+1, j--
print j and "*";
print j and new line```

## C++

 `// C++ implementation to print the following ``// pyramid pattern ``#include  ``using` `namespace` `std; `` ` `// function to print the following pyramid pattern ``void` `printPattern(``int` `n) ``{ ``    ``int` `j, k = 0; ``     ` `    ``// loop to decide the row number ``    ``for` `(``int` `i=1; i<=n; i++) ``    ``{ ``        ``// if row number is odd ``        ``if` `(i%2 != 0) ``        ``{ ``            ``// print numbers with the '*' sign in ``            ``// increasing order ``            ``for` `(j=k+1; jk-i+1; j--) ``                ``cout << j << ``"*"``; ``            ``cout << j << endl;     ``        ``} ``    ``} ``} `` ` `// Driver program to test above ``int` `main() ``{ ``    ``int` `n = 5; ``    ``printPattern(n); ``    ``return` `0; ``} `

## Java

 `// Java implementation to print the ``// following pyramid pattern ``public` `class` `Pyramid_Pattern { `` ` `    ``// function to print the following pyramid ``    ``// pattern ``    ``static` `void` `printPattern(``int` `n) ``    ``{ ``        ``int` `j, k = ``0``; `` ` `        ``// loop to decide the row number ``        ``for` `(``int` `i = ``1``; i <= n; i++) { ``             ` `            ``// if row number is odd ``            ``if` `(i % ``2` `!= ``0``) { ``             ` `                ``// print numbers with the '*' ``                ``// sign in increasing order ``                ``for` `(j = k + ``1``; j < k + i; j++) ``                    ``System.out.print(j + ``"*"``); ``                ``System.out.println(j++); `` ` `                ``// update value of 'k' ``                ``k = j; ``            ``} `` ` `            ``// if row number is even ``            ``else` `{ ``                 ` `                ``// update value of 'k' ``                ``k = k + i - ``1``; `` ` `                ``// print numbers with the '*' in ``                ``// decreasing order ``                ``for` `(j = k; j > k - i + ``1``; j--) ``                    ``System.out.print(j + ``"*"``); ``                ``System.out.println(j); ``            ``} ``        ``} ``    ``} `` ` `    ``// Driver program to test above ``public` `static` `void` `main(String args[]) ``    ``{ ``        ``int` `n = ``5``; ``        ``printPattern(n); ``    ``} ``} ``// This code is contributed by Sumit Ghosh `

## Python3

 `# Python3 implementation to print the ``# following pyramid pattern `` ` `# function to print the ``# following pyramid pattern ``def` `printPattern(n) : `` ` `    ``j, k ``=` `0``, ``0`` ` `    ``# loop to decide the row number ``    ``for` `i ``in` `range``(``1``, n ``+` `1``) : `` ` `        ``# if row number is odd ``        ``if` `i ``%` `2` `!``=` `0` `: `` ` `            ``# print numbers with ``            ``# the '*' sign in ``            ``# increasing order ``            ``for` `j ``in` `range``(k ``+` `1``, k ``+` `i) : `` ` `                ``print``(``str``(j) ``+` `"*"``, ``                        ``end ``=` `"") `` ` `            ``j ``=` `k ``+` `i ``            ``print``(j) ``            ``j ``+``=` `1`` ` `            ``# update value of 'k' ``            ``k ``=` `j `` ` `        ``# if row number is even ``        ``else` `: `` ` `            ``# update value of 'k' ``            ``k ``=` `k ``+` `i ``-` `1`` ` `            ``# print numbers with the ``            ``# '*' in decreasing order ``            ``for` `j ``in` `range``(k, k ``-` `i ``+` `1``, ``-``1``) : ``                ``print``(``str``(j) ``+` `"*"``, end ``=` `"") `` ` `            ``j ``=` `k ``-` `i ``+` `1``            ``print``(j) `` ` `# Driver Code ``if` `__name__ ``=``=` `"__main__"` `: ``    ``n ``=` `5`` ` `    ``# function calling ``    ``printPattern(n) ``             ` `# This code is contributed ``# by ANKITRAI1 `

## C#

 `// C# implementation to print the ``// following pyramid pattern ``using` `System; ``public` `class` `Pyramid_Pattern { `` ` `    ``// function to print the following pyramid ``    ``// pattern ``    ``static` `void` `printPattern(``int` `n) ``    ``{ ``        ``int` `j, k = 0; `` ` `        ``// loop to decide the row number ``        ``for` `(``int` `i = 1; i <= n; i++) { ``             ` `            ``// if row number is odd ``            ``if` `(i % 2 != 0) { ``             ` `                ``// print numbers with the '*' ``                ``// sign in increasing order ``                ``for` `(j = k + 1; j < k + i; j++) ``                    ``Console.Write(j + ``"*"``); ``                ``Console.WriteLine(j++); `` ` `                ``// update value of 'k' ``                ``k = j; ``            ``} `` ` `            ``// if row number is even ``            ``else` `{ ``                 ` `                ``// update value of 'k' ``                ``k = k + i - 1; `` ` `                ``// print numbers with the '*' in ``                ``// decreasing order ``                ``for` `(j = k; j > k - i + 1; j--) ``                    ``Console.Write(j + ``"*"``); ``                    ``Console.WriteLine(j); ``            ``} ``        ``} ``    ``} `` ` `    ``// Driver program to test above ``public` `static` `void` `Main() ``    ``{ ``        ``int` `n = 5; ``        ``printPattern(n); ``    ``} ``} ``// This code is contributed by vt_m. `

## PHP

 ` ``\$k` `- ``\$i` `+ 1; ``\$j``--) ``                ``echo` `\$j` `. ``"*"``; ``            ``echo` `\$j` `.``"\n"` `; ``        ``} ``    ``} ``} `` ` `    ``// Driver Code ``    ``\$n` `= 5; ``    ``printPattern(``\$n``); `` ` `// This code is contributed by Sam007 ``?> `

## Javascript

 ``

Output:

```1
3*2
4*5*6
10*9*8*7
11*12*13*14*15```

Time Complexity: O((n * (n + 1)) / 2)

Space Complexity: O(1) since using constant variables, since no extra space has been taken.

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