From 01f6fc2168c8612b4465f73909ec2d93025b337b Mon Sep 17 00:00:00 2001
From: Ray <sympatheticfire@gmail.com>
Date: Fri, 4 Aug 2023 23:57:53 +0100
Subject: [PATCH] Recovered missing file

---
 2021/02/SpreadsheetCoord.cs | 199 ++++++++++++++++++++++++++++++++++++
 1 file changed, 199 insertions(+)
 create mode 100644 2021/02/SpreadsheetCoord.cs

diff --git a/2021/02/SpreadsheetCoord.cs b/2021/02/SpreadsheetCoord.cs
new file mode 100644
index 0000000..bbe30a1
--- /dev/null
+++ b/2021/02/SpreadsheetCoord.cs
@@ -0,0 +1,199 @@
+using System;
+
+namespace WindowsFormsApp1
+{
+    public class SpreadsheetCoord
+    {
+        public static string ConvertToColumnCode(int columnNo, int rowNo)
+        {
+            if ((columnNo <= 0) || (rowNo <= 0)) return null;
+
+            string rs = string.Empty;
+
+            int x = 790;
+            while (x > 0)
+            {
+                int n = (x % 26);
+
+                rs = Convert.ToChar(65 + n - 1) + rs;
+
+                x -= n;
+                x = (x / 26);
+            }
+
+            return string.Concat(rs, rowNo.ToString());
+        }
+
+        public static Tuple<int, int> ConvertToCoord(string value)
+        {
+            bool checkAlpha = true;
+            string alpha = string.Empty;
+            string digit = string.Empty;
+
+            for (int i = 0; i < value.Length; i++)
+            {
+                if (checkAlpha)
+                {
+                    if (isAlpha(value[i]))
+                    {
+                        alpha += value[i];
+                    }
+                    else if (isDigit(value[i]))
+                    {
+                        digit += value[i];
+
+                        checkAlpha = false;
+                    }
+                    else
+                    {
+                        return null;
+                    }
+                }
+                else
+                {
+                    if (isAlpha(value[i]))
+                    {
+                        return null;
+                    }
+                    else if (isDigit(value[i]))
+                    {
+                        digit += value[i];
+                    }
+                    else
+                    {
+                        return null;
+                    }
+                }
+            }
+
+            // no alpha or digits
+            if ((alpha.Length <= 0) || (digit.Length <= 0))
+            {
+                return null;
+            }
+
+            int rowNo;
+            if (!int.TryParse(digit, out rowNo))
+            {
+                return null;
+            }
+
+            if (rowNo <= 0)
+            {
+                return null;
+            }
+
+            int columnNo = convertColumn(alpha);
+
+            return new Tuple<int, int>(columnNo, rowNo);
+        }
+
+        public static bool IsValid(string value)
+        {
+            bool checkAlpha = true;
+            string alpha = string.Empty;
+            string digit = string.Empty;
+
+            for (int i = 0; i < value.Length; i++)
+            {
+                if (checkAlpha)
+                {
+                    if (isAlpha(value[i]))
+                    {
+                        alpha += value[i];
+                    }
+                    else if (isDigit(value[i]))
+                    {
+                        digit += value[i];
+
+                        checkAlpha = false;
+                    }
+                    else
+                    {
+                        return false;
+                    }
+                }
+                else
+                {
+                    if (isAlpha(value[i]))
+                    {
+                        return false;
+                    }
+                    else if (isDigit(value[i]))
+                    {
+                        digit += value[i];
+                    }
+                    else
+                    {
+                        return false;
+                    }
+                }
+            }
+
+            // no alpha or digits
+            if ((alpha.Length <= 0) || (digit.Length <= 0))
+            {
+                return false;
+            }
+
+            int n;
+            if (!int.TryParse(digit, out n))
+            {
+                return false;
+            }
+
+            if (n <= 0)
+            {
+                return false;
+            }
+
+            return true;
+        }
+
+        protected static int convertColumn(string value)
+        {
+            int rv = 0;
+
+            int len = value.Length - 1;
+            for (int i = len; i >= 0; i--)
+            {
+                int n = (len - i);
+                int x = convertColumn(value[i]);
+
+                rv += (int)(x * Math.Pow(26, n));
+            }
+
+            return rv;
+        }
+
+        protected static int convertColumn(char value)
+        {
+            if (isAlpha(value))
+            {
+                int code = Convert.ToInt16(char.ToUpper(value));
+
+                return (code - 65) + 1;
+            }
+            else
+            {
+                return 0;
+            }
+        }
+
+
+        protected static bool isAlpha(char value)
+        {
+            int code = Convert.ToInt16(char.ToUpper(value));
+
+            return ((code >= 65) && (code <= 90));
+        }
+
+        protected static bool isDigit(char value)
+        {
+            int code = Convert.ToInt16(char.ToUpper(value));
+
+            return ((code >= 48) && (code <= 57));
+        }
+
+    }
+}