Initial commit, prep

src/Util/Math.cs

@@ -0,0 +1,65 @@
+namespace aoc2023.Util;
+
+public static class Math
+{
+    public static ulong GCD(ulong a, ulong b)
+    {
+        while (true)
+        {
+            if (b == 0)
+            {
+                return a;
+            }
+
+            var a1 = a;
+            a = b;
+            b = a1 % b;
+        }
+    }
+
+    public static ulong LCM(params ulong[] nums)
+    {
+        var num = nums.Length;
+        switch (num)
+        {
+            case 0:
+                return 0;
+            case 1:
+                return nums[0];
+        }
+
+        var ret = lcm(nums[0], nums[1]);
+        for (var i = 2; i < num; i++)
+        {
+            ret = lcm(nums[i], ret);
+        }
+
+        return ret;
+    }
+
+    private static ulong lcm(ulong a, ulong b)
+    {
+        return (a * b) / GCD(a, b);
+    }
+
+    public static long Modulo(long numer, long denom)
+    {
+        // long q = numer / denom;
+        long r = numer % denom;
+        if (r < 0)
+        {
+            if (denom > 0)
+            {
+                // q = q - 1;
+                r = r + denom;
+            }
+            else
+            {
+                // q = q + 1;
+                r = r - denom;
+            }
+        }
+
+        return r;
+    }
+}