Last Updated: 27 Nov, 2020

Arrow Pattern

Easy

Problem statement

You are given an integer 'N'. Your task is to give a pattern with the following description:

1. The pattern will consist of 2 * ‘N’ - 1 lines.
2. The pattern will consist of ‘ ’ (space) and ‘*’ (asterisk) characters only.
3. The pattern will be an arrow pattern.
4. For a value 'i', the arrow pattern starts with 'i' ‘ ’ (space) characters and then has 'i' ‘*’ (asterisk) characters.
5. The value of 'i' starts from 1, increases till ‘N’ and then decreases till 1.

Please note that each line will consist of the same number of ‘ ’ and ‘*’ characters.

For a better understanding of the arrow, pattern refers to example and sample input-output.

For example:

If ‘N’ is 5 then the pattern will be (there is a space before the first asterisk):

 *
  **
   ***
    ****
     *****
    ****
   ***
  **
 *

Input Format

The first line of input contains an integer 'T' representing the number of test cases.

Then each test case contains a single integer ‘N’ denoting the size of the pattern.

Output Format:

For each test case, print the 'N' strings denoting the pattern.

The output of each test case will be printed in a separate line.

Constraints:

1 <= 'T' <= 10
1 <= 'N' <= 1000

Where ‘T’ is the number of test cases, ‘N’  is the size of the pattern.

Note:

You do not need to print anything, it has already been taken care of. Just implement the given function.

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Approaches

01 Approach

The idea is here to maintain 2 strings 1 for ‘ ‘ characters and 1 for ‘*’ characters, now in each step till ‘N’ we will append 1 ‘ ‘ character in 1st string and 1 ‘*’ character in 2nd string. After ‘N’ in each step, we will remove 1 ‘ ‘ character from the 1st string and 1 ‘*’ character from the 2nd string. At each step, we will append concatenation of both strings to our pattern.

Algorithm:

Create 2 strings name ‘str1’ and ‘str2’, ‘str1’ is for ‘ ‘ characters and ‘str2’ is for ‘*’ characters. Also, create an array of strings for storing the pattern say ‘answer’.
Run a loop from ‘i’ = 1 to ‘i’ = 2 * ‘N’ - 1
If ‘i’ <= ‘N’ append ‘ ‘ to ‘str1’ and ‘*’ to ‘str2’ now append ‘str1’ + ‘str2’ to ‘answer’.
Else, remove 1 character from ‘str1’ and 1 character from ‘str2’ and append ‘str1’ + ‘str2’ to ‘answer’.
Return the ‘answer’ array that contains the pattern.

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