feat: fetch problem by pwsh script.

Remove old C++ fetcher.

build.ps1

@@ -0,0 +1,89 @@
+#!pwsh
+
+[CmdletBinding()]
+param(
+    [Parameter(Mandatory = $true, Position = 0)]
+    [string]$problemId
+)
+
+begin
+{
+    $ErrorActionPreference = 'Stop'
+}
+
+end
+{
+    Write-Host "Try to fetch problem $($problemId)"
+
+    $graphQuery = @'
+query questionData($titleSlug: String!) {
+question(titleSlug: $titleSlug) {
+content
+stats
+codeDefinition
+sampleTestCase
+metaData
+}
+}
+'@
+    $response = Invoke-RestMethod -Uri "https://leetcode.cn/api/problems/algorithms/" -Method Get
+    $problem = @($response.stat_status_pairs | Where-Object { $_.stat.frontend_question_id -eq $problemId })
+
+    if ($problem.Count -ne 1)
+    {
+        Write-Error "Failed to find target problem $($problemId)"
+    }
+    $problem = $problem[0]
+
+    $problemNumber = "{0:D4}" -f ($problem.stat.frontend_question_id -as [int])
+    $filename = "$problemNumber-$($problem.stat.question__title_slug).cpp"
+
+    $existedFile = @(Get-ChildItem ./src/problems | Where-Object { $_.Name -eq $filename})
+
+    if ($existedFile.Count -gt 0)
+    {
+        Write-Error "Problem $($problem.stat.question__title_slug) has been fetched, see src/problems/$filename."
+    }
+
+    $variables = @{
+        titleSlug = $problem.stat.question__title_slug
+    } | ConvertTo-Json
+
+    $query = @{
+        operationName = "questionData"
+        variables = $variables
+        query = $graphQuery
+    }
+
+    Write-Host "Try to fetch details of $($problem.stat.question__title_slug)"
+    $response = Invoke-RestMethod -Uri "https://leetcode.cn/graphql" -Body $query -Method Post
+
+    $codeDefinition = @($response.data.question.codeDefinition | ConvertFrom-Json | Where-Object { $_.value -eq "cpp" })
+    if ($codeDefinition.Count -ne 1)
+    {
+        Write-Error "Failed to find C++ code definition"
+    }
+    $testcaseName = "P$($problem.stat.frontend_question_id)"
+
+    $outputCode = @"
+/**
+* [$($problem.stat.frontend_question_id)] $($problem.stat.question__title_slug)
+*/
+#include <gtest/gtest.h>
+using namespace std;
+
+
+// submission codes start here
+
+$($codeDefinition[0].defaultCode)
+
+// submission codes end
+
+TEST($testcaseName, Test1)
+{
+}
+"@
+
+    Set-Content -Path "./src/problems/$($filename)" -Value $outputCode
+    Write-Host "Saved as $filename."
+}