From db9e9a33f428a8994122a3b32f04b3a4fd611814 Mon Sep 17 00:00:00 2001
From: Colin McMillen <colin@semicolin.games>
Date: Tue, 17 Nov 2020 14:36:40 -0500
Subject: [PATCH] problem 5 solution

---
 Program.cs | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/Program.cs b/Program.cs
index 4ab91d3..380abb3 100644
--- a/Program.cs
+++ b/Program.cs
@@ -5,6 +5,18 @@ namespace Euler {
 
   class Program {
 
+  	static void Debug(long l) {
+  		Console.WriteLine(l);
+  	}
+
+  	static void Debug(string s) {
+  		Console.WriteLine(s);
+  	}
+
+  	static void Debug(bool b) {
+  		Console.WriteLine(b);
+  	}
+
   	static long Problem1() {
   		long sum = 0;
   		for (long i = 1; i < 1000; i++) {
@@ -70,8 +82,35 @@ namespace Euler {
   		return highestPrimeFactor;
   	}
 
+  	static bool IsPalindromicNumber(long l) {
+  		string s = "" + l;
+  		for (int i = 0; i < s.Length / 2; i++) {
+  			if (s[i] != s[s.Length - i - 1]) {
+  				return false;
+  			}
+  		}
+  		return true;
+  	}
+
+  	static long Problem4() {
+  		long largest = 0;
+  		for (long i = 999; i >= 100; i--) {
+  			for (long j = 999; j >= 100; j--) {
+  				long target = i * j;
+  				if (target < largest) {
+  					continue;
+  				}
+  				if (IsPalindromicNumber(target)) {
+  					largest = target;
+  					Debug(largest);
+  				}
+  			}
+  		}
+  		return largest;
+  	}
+
     static void Main(string[] args) {
-      Console.WriteLine(Problem3());
+      Debug(Problem4());
     }
   }
 }
\ No newline at end of file