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- Type: Post or Video plus Feature As a Feature post or video, it also serves to the home page as a Latest Post or Latest Video. Consider only having 1-3 Feature at a time to avoid cluttering the page.
- Status: Live - a post or video marked as Draft will not serve to this page or the home page.
- Type: Post or Video
- Status: Live
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- Adventures in Leet Code: PowerShell Twist
- Useful Constructs
- For Loops
- Problems
- 1- Add Binary Strings
- My Solution
- Test it
- 2 - Remove All Adjacent Duplicates In String
- Problem
- My Solution
- Test it
- 3 - Valid Word Abbreviation
- My Solution
- Test it
- 4 - Valid Palindrome II
- My Solution
- Test it
- 5 - Valid Phone Number
- Test It
- 6 - Lines in a given range
- Test It
- 7 - Remove Punctuations
- My Solution
- Test it
- 8 - Majority Element
- My solution
- Test It
- 9 - Reverse Words in a String
- My Solution
- Test It
- 10 - Word Break
- My Solution
- Test it
Adventures in Leet Code: PowerShell Twist
I’ve been looking into new challenges recently and decided to give LeetCode a shot. I quickly realized that I haven’t been working on this kind of problem since I took a couple programming classes where I didn’t learn much. Leetcode doesn’t support PowerShell, so I’m going to post these here.
I found that I was having to look up things that I haven’t encountered much while using PowerShell. I really enjoy how these are pushing me to grow. This blog post aims to share some problems and solutions that I’ve worked on.
Useful Constructs
For Loops
A For loop is a great way to iterate on a subset of a collection of items. Oftentimes, foreach is more appropriate, but I’ve found the for loop to be useful in a lot of leetcode questions.
# Reverse a string with a for loop
$string = 'Jill loves cars.'
# make sure to use the length property instead of count when dealing with manipulating characters in a string
$output = for ($i = 1 ; $i -le $string.length; $i++) {
$string[-$i] # output each character, starting at the back
}
# $output is an array, rather than a string. We need to -join them back together again <3
$output -join ''Problems
1- Add Binary Strings
Given two binary strings a and b, return their sum as a binary string.
Example 1:
Input: a = “11”, b = “1” Output: “100”
My Solution
function Convert-BinaryStringtoInteger {
[CmdletBinding()]
param(
[Parameter(Mandatory)]
[int]$a,
[Parameter(Mandatory)]
[int]$b
)
$aInt = [Convert]::ToInt32($a,2)
$bInt = [Convert]::ToInt32($b,2)
$cInt = $aInt + $bInt
$cBinaryString = [Convert]::ToString($cInt,2)
Write-Output $cBinaryString
}Test it
Convert-BinaryStringtoInteger -a 11 -b 1
100
Convert-BinaryStringtoInteger -a 1010 -b 1011
101012 - Remove All Adjacent Duplicates In String
Problem
Remove All Adjacent Duplicates In String. You are given a string s consisting of lowercase English letters. A duplicate removal consists of choosing two adjacent and equal letters and removing them.
We repeatedly make duplicate removals on s until we no longer can.
Return the final string after all such duplicate removals have been made. It can be proven that the answer is unique.
My Solution
function Remove-AdjacentDuplicates {
param(
[Parameter(Mandatory)]
[ValidateScript({
if (-not ($_ -cmatch '[a-z]')) {
throw 'lowercase English letters only'
}
else { $true }
})]
[ValidateLength(1, 100000)]
[string]
$s
)
for ($i = 0; $i -lt $s.length ; $i++) {
if ($s[$i] -eq $s[$i + 1]) {
$stringToReplace = "$($s[$i])$( $s[ $i + 1 ])"
$s = $s.replace($stringtoReplace, '')
$i = -1 # set to negative because it get +1 every iteration and we want it to be on 0
}
}
Write-Output $s
}Test it
Remove-AdjacentDuplicates -s abbaca
ca
Remove-AdjacentDuplicates -s azxxzy
ay3 - Valid Word Abbreviation
Given a string word and an abbreviation abbr, return whether the string matches the given abbreviation.
A substring is a contiguous non-empty sequence of characters within a string.
My Solution
function Test-ValidWordAbbreviation {
param(
[Parameter(Mandatory)]
[ValidateLength(1, 20)]
[ValidateScript({
if ($_ -cmatch '[a-z]0') {
throw "No leading zeros"
}
if ($_ -cmatch '[A-Z]') {
throw "No capital letters"
}
else { $true }
})]
[string]$Word,
[Parameter(Mandatory)]
[ValidateLength(1, 10)]
[string]$Abbr
)
$replacedAbbr = $Abbr
$pattern = '\d{1,}' # 1 or more digits
$matches = [regex]::Matches($replacedAbbr , $pattern)
for ($i = 0; $i -lt $matches.Count; $i++) {
$numbers = [regex]::Matches($replacedAbbr , $pattern)
[int]$upperBound = $numbers[0].Index + $numbers[0].value - 1
$replacementText = $word[ $numbers[0].index..$upperBound ] -join ''
$replacedAbbr = $replacedAbbr.Replace( $numbers[0].Value , $replacementText )
}
if ($replacedAbbr -eq $Word) { Write-Output $true }
else { Write-Output $false }
}Test it
Test-ValidWordAbbreviation -Word internationalization -Abbr i12iz4n
True
Test-ValidWordAbbreviation -Word a2e -Abbr apple
False4 - Valid Palindrome II
Given a string s, return true if the s can be palindrome after deleting at most one character from it.
My Solution
function Test-ValidPalindromeII {
param(
[Parameter(Mandatory)]
[ValidateLength(1, 100000)]
[ValidateScript({
if ($_ -cmatch '[A-Z]') {
throw 'lowercase English letters only'
}
else {
Write-Output $true
}
})]
[string]
$s
)
# See if it's a palindrome as-is
$reversedWord = for ($j = 1; $j -le $s.length; $j++) {
$s[ - $j ]
}
$reversedWord = $reversedWord -join ''
if ($reversedWord -eq $s) { $Palindrome = $true }
# Iterate through and remove a character then test if it's a palindrome
for ($i = 0; $i -lt $s.length; $i++) {
# break from loop if $Palindrome is set to $true
if ($Palindrome) { break }
$replacedWord = $s.remove($i, 1)
$reversedWord = for ($j = 1; $j -le $replacedWord.length; $j++) {
$replacedWord[ - $j ]
}
$reversedWord = $reversedWord -join ''
if ($reversedWord -eq $replacedWord) {
$Palindrome = $true
}
}
if ($Palindrome) {
Write-Output $true
}
else { Write-Output $false }
}Test it
Test-ValidPalindromeII -s 'aba'
True
Test-ValidPalindromeII -s 'abca'
True
Test-ValidPalindromeII -s 'abc'
False5 - Valid Phone Number
Given a text file input that contains list of phone numbers (one per line).
Write a bash script to print all valid phone numbers.You may assume that a valid phone number must appear in one of the following two formats:
- xxx-xxxx xxx-xxx-xxxx You may also assume each line in the text file must not contain leading or trailing white spaces.
function Get-ValidPhoneNumber {
param(
[Parameter(Mandatory)]
[string[]]$Numbers
)
foreach($number in $Numbers){
if ($number -match '^\(\d{3}\) \d{3}-\d{4}$'){
Write-Output $number
}
if ($number -match '^\d{3}-\d{3}-\d{4}$') {
Write-Output $number
}
}
}Test It
$numbers = "987-123-4567", "123 456 7890","(123) 456-7890"
Get-ValidPhoneNumber -Numbers $numbers6 - Lines in a given range
Write a bash script to print all the lines of the input which are in the given range. The first line of the input contains two integers l and r separated by space. You have to print all the lines of the file input which are in the range of [l, r].
function Get-LinesinGivenRange {
param(
[Parameter(Mandatory)]
[string[]]
$InputContent
)
$ranges = ($InputContent -split "`n")[0].trim() -split ' '
$InputContent = $InputContent -split "`n"
$InputContent[( $range[0] -1 )..( $range[1] -1 )]
}Test It
$content = "10 15
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
Line 8
Line 9
Line 10
Line 11
Line 12
Line 13
Line 14
Line 15
Line 16
Line 17
Line 18
Line 19
Line 20"
Get-LinesinGivenRange -Input $content -Range 10,157 - Remove Punctuations
Write a bash script that removes all the punctuations in the given file named input For this question, assume that all of the following symbols are punctuations: ! @ # $ % ^ & * ( ) _ - + = { } [ ] ; : ’ " ` / > ? . , < ~ |
Example:
Assume that input has the following content:
This’s the sunny day. It is the sunny day, we can go out. Your script should output the following:
Thiss the sunny day It is the sunny day we can go out
My Solution
function Remove-Punctuation {
param(
[Parameter(Mandatory)]
[string]
$InputContent
)
$characters = '!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '_', '-', '+', '=', '{', '}', '[', ']', ';', ':', "'", '"', '`', '/', '>', '?', '.', ',', '<', '~', '|', '\'
$characters | Foreach-Object {
$InputContent = $InputContent.replace($_, '')
}
Write-Output $InputContent
}Test it
$string = "This's the sunny day.
It is the sunny day, we can go out."
Remove-Punctuation -InputContent $string
Thiss the sunny day
It is the sunny day we can go out8 - Majority Element
Given an array of size n, find the majority element. The majority element is the element that appears more than floor(n/2) times. You may assume that the array is non-empty and the majority element always exist in the array.
Example :
Input : [2, 1, 2] Return : 2 which occurs 2 times which is greater than 3/2.
My solution
function Get-Solution {
[CmdletBinding()]
param (
[int[]]$Numbers
)
$numbers | Where-Object {$_ -gt ($Numbers.count / 2) } | Select-Object -First 1
}Test It
Get-Solution -Numbers 2,1,2
29 - Reverse Words in a String
Given an input string s, reverse the order of the words.
A word is defined as a sequence of non-space characters. The words in s will be separated by at least one space.
Return a string of the words in reverse order concatenated by a single space.
Note that s may contain leading or trailing spaces or multiple spaces between two words. The returned string should only have a single space separating the words. Do not include any extra spaces.
My Solution
function Reverse-WordsinString {
[CmdletBinding()]
param(
[Parameter(Mandatory)]
[string]$S
)
$words = ($S -split ' ').trim() # Split the words and remove extra spaces
# the skye is blue
$output = for ($i = 1; $i -le $words.count; $i++){
$words[-$i] | Where-Object {$_ -Match '\w'} # only grab words, not blank lines
}
$output -join ' '
}Test It
Reverse-WordsinString -S "the skye is blue"
blue is skye the
Reverse-WordsinString -S " Bob Loves Alice "
Alice Loves Bob
Reverse-WordsinString -S "Alice does not even like bob"
bob like even not does Alice10 - Word Break
Given a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words.
Note that the same word in the dictionary may be reused multiple times in the segmentation.
Example 1:
Input: s = “leetcode”, wordDict = [“leet”,“code”] Output: true Explanation: Return true because “leetcode” can be segmented as “leet code”. Example 2:
Input: s = “applepenapple”, wordDict = [“apple”,“pen”] Output: true Explanation: Return true because “applepenapple” can be segmented as “apple pen apple”. Note that you are allowed to reuse a dictionary word. Example 3:
Input: s = “catsandog”, wordDict = [“cats”,“dog”,“sand”,“and”,“cat”] Output: false
My Solution
function Test-WordBreak {
[CmdletBinding()]
param(
[Parameter(Mandatory)]
[string]$s,
[Parameter(Mandatory)]
[string[]]$WordDict
)
$remainingWords = $s
foreach ($word in $WordDict ) {
$remainingWords = $remainingWords -split $word
}
if ( ( $remainingWords | Where-Object { $_ -match '\w' }) -gt 0) {
return $false
}
else {
return $true
}
}Test it
test-wordbreak -s leetcode -worddict 'leet','code'
True
test-wordbreak -s applepenapple -worddict 'apple','pen'
True
test-wordbreak -s catsandog -WordDict 'cats','dog','sand','and','cat'
False