From 08a76ad16ee62b2cbb2cda3508445047f2ff9cf1 Mon Sep 17 00:00:00 2001
From: Mohammad S Anwar <mohammad.anwar@yahoo.com>
Date: Tue, 11 Jan 2022 17:56:41 +0000
Subject: - Added guest contributions by Eric Cheung.

---
 .../eric-cheung/excel-vba/Challenge_147.xlsm       | Bin 0 -> 25600 bytes
 challenge-147/eric-cheung/excel-vba/ch-1.bas       |  86 +++++++++++++++++++++
 challenge-147/eric-cheung/python/ch-2.py           |  45 +++++++++++
 3 files changed, 131 insertions(+)
 create mode 100755 challenge-147/eric-cheung/excel-vba/Challenge_147.xlsm
 create mode 100755 challenge-147/eric-cheung/excel-vba/ch-1.bas
 create mode 100755 challenge-147/eric-cheung/python/ch-2.py

diff --git a/challenge-147/eric-cheung/excel-vba/Challenge_147.xlsm b/challenge-147/eric-cheung/excel-vba/Challenge_147.xlsm
new file mode 100755
index 0000000000..6f7427aff8
Binary files /dev/null and b/challenge-147/eric-cheung/excel-vba/Challenge_147.xlsm differ
diff --git a/challenge-147/eric-cheung/excel-vba/ch-1.bas b/challenge-147/eric-cheung/excel-vba/ch-1.bas
new file mode 100755
index 0000000000..558dd6656c
--- /dev/null
+++ b/challenge-147/eric-cheung/excel-vba/ch-1.bas
@@ -0,0 +1,86 @@
+Attribute VB_Name = "ModTask_01"
+Option Explicit
+
+Public Const strMyTitle As String = "Eric Cheung"
+
+Option Base 1
+Public nPrimeArr() As Long
+Public nPrimeCnt As Integer
+
+Function IsPrime(nInput As Integer) As Boolean
+
+    Dim nNumLoop As Integer
+    
+    If nInput = 1 Then
+        IsPrime = False
+        Exit Function
+    End If
+    
+    For nNumLoop = LBound(nPrimeArr) To UBound(nPrimeArr)
+        If nInput = nPrimeArr(nNumLoop) Then
+            IsPrime = True
+            Exit Function
+        ElseIf nInput Mod nPrimeArr(nNumLoop) = 0 Then
+            IsPrime = False
+            Exit Function
+        End If
+    Next nNumLoop
+
+    IsPrime = True
+    
+End Function
+
+Function IsTruncatablePrime(nInput As Integer) As Boolean
+
+    If nInput = 0 Then
+        IsTruncatablePrime = False
+        Exit Function
+    ElseIf Not IsPrime(nInput) Then
+        IsTruncatablePrime = False
+        Exit Function
+    End If
+    
+    nPrimeCnt = nPrimeCnt + 1
+    ReDim Preserve nPrimeArr(1 To nPrimeCnt)
+    nPrimeArr(nPrimeCnt) = nInput
+    
+    If nInput < 10 Then
+        IsTruncatablePrime = True
+    Else
+        If Val(Mid(CStr(nInput), 2, 1)) = 0 Then
+            IsTruncatablePrime = False
+            Exit Function
+        End If
+        IsTruncatablePrime = IsTruncatablePrime(Val(Right(CStr(nInput), Len(CStr(nInput)) - 1)))
+    End If
+    
+End Function
+
+Sub Task_01()
+
+    Const nTruncatablePrimeCntMax As Integer = 20
+
+    Dim nLoop As Integer, nTruncatablePrimeCnt As Integer
+    Dim strMsg As String
+    
+    ReDim nPrimeArr(1 To 1)
+    
+    nPrimeCnt = 1
+    nPrimeArr(1) = 2
+    nLoop = 3
+    
+    nTruncatablePrimeCnt = 1
+    
+    strMsg = "First " & nTruncatablePrimeCntMax & " left-truncatable prime numbers in base 10 are: " & 2
+
+    Do While (nTruncatablePrimeCnt < nTruncatablePrimeCntMax)
+        If IsTruncatablePrime(nLoop) Then
+            strMsg = strMsg & ", " & nLoop
+            nTruncatablePrimeCnt = nTruncatablePrimeCnt + 1
+        End If
+        nLoop = nLoop + 1
+    Loop
+
+    MsgBox strMsg, vbOKOnly, strMyTitle
+
+End Sub
diff --git a/challenge-147/eric-cheung/python/ch-2.py b/challenge-147/eric-cheung/python/ch-2.py
new file mode 100755
index 0000000000..6a716b2ddd
--- /dev/null
+++ b/challenge-147/eric-cheung/python/ch-2.py
@@ -0,0 +1,45 @@
+## Remarks
+## https://www.mathblog.dk/project-euler-44-smallest-pair-pentagonal-numbers/
+## https://radiusofcircle.blogspot.com/2016/06/problem-44-project-euler-solution-with-python.html
+## http://radiusofcircle.blogspot.com
+
+## Time Module for Calculating Execution Time
+import time
+
+## Time At The Start of Program Execution
+dStartTime = time.time()
+
+def is_pentagonal(nInput):
+    ## Function To Check If The Number is Pentagonal Number or Not
+    if (1 + (24 * nInput + 1) ** 0.5) % 6 == 0:
+        return True
+    return False
+
+## Flag To Check If The Number Is Found Or Not
+bFlag = True
+
+# While Loop Iterator
+nLoop = 1
+
+# While Loop
+while bFlag:
+    nNum_01 = nLoop * (3 * nLoop - 1) / 2
+    for nSubLoop in range(1, nLoop):
+        nNum_02 = nSubLoop * (3 * nSubLoop - 1) / 2
+        if is_pentagonal(nNum_01 + nNum_02) and is_pentagonal(nNum_01 - nNum_02):
+            print ("nLoop = " + str(nLoop) + ", nSubLoop = " + str(nSubLoop))
+            bFlag = False
+            break
+    nLoop = nLoop + 1
+
+# Time At The End of Program Execution
+dEndTime = time.time()
+
+# Printing The Total Time For Execution
+print ("Time Needed: " + str(dEndTime - dStartTime))
+
+
+## Result
+## nLoop = 2167, nSubLoop = 1020
+## Time Needed: 1.1174473762512207
+
-- 
cgit