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