Add Palindromic Number in Beef (#3734)

archive/b/beef/PalindromicNumber.bf

@@ -0,0 +1,69 @@
+using System;
+
+namespace PalindromicNumber;
+
+class Program
+{
+    public static void Usage()
+    {
+        Console.WriteLine("Usage: please input a non-negative integer");
+        Environment.Exit(0);
+    }
+
+    public static Result<T> ParseInt<T>(StringView str)
+    where T : IParseable<T>
+    {
+        StringView trimmedStr = scope String(str);
+        trimmedStr.Trim();
+
+        // T.Parse ignores single quotes since they are treat as digit separators -- e.g. 1'000
+        if (trimmedStr.Contains('\''))
+        {
+            return .Err;
+        }
+
+        return T.Parse(trimmedStr);
+    }
+
+    public static bool PalindromicNumber<T>(T val)
+    where T: IInteger
+    {
+        String str = scope String();
+        val.ToString(str);
+        bool isPalindromic = true;
+        for (int left = 0, right = str.Length - 1; left < right; left++, right--)
+        {
+            if (str[left] != str[right])
+            {
+                isPalindromic = false;
+                break;
+            }
+        }
+
+        return isPalindromic;
+    }
+
+    public static int Main(String[] args)
+    {
+        if (args.Count < 1 || args[0].Length < 1)
+        {
+            Usage();
+        }
+
+        int32 val = 0;
+        switch (ParseInt<int32>(args[0]))
+        {
+            case .Ok(out val):
+                if (val < 0)
+                {
+                    Usage();
+                }
+            case .Err:
+                Usage();
+        }
+
+        bool result = PalindromicNumber<int32>(val);
+        Console.WriteLine(result ? "true" : "false");
+        return 0;
+    }
+}