Initial data commit

Task/Pythagorean-quadruples/C-sharp/pythagorean-quadruples.cs

@@ -0,0 +1,38 @@
+using System;
+
+namespace PythagoreanQuadruples {
+    class Program {
+        const int MAX = 2200;
+        const int MAX2 = MAX * MAX * 2;
+
+        static void Main(string[] args) {
+            bool[] found = new bool[MAX + 1]; // all false by default
+            bool[] a2b2 = new bool[MAX2 + 1]; // ditto
+            int s = 3;
+
+            for(int a = 1; a <= MAX; a++) {
+                int a2 = a * a;
+                for (int b=a; b<=MAX; b++) {
+                    a2b2[a2 + b * b] = true;
+                }
+            }
+
+            for (int c = 1; c <= MAX; c++) {
+                int s1 = s;
+                s += 2;
+                int s2 = s;
+                for (int d = c + 1; d <= MAX; d++) {
+                    if (a2b2[s1]) found[d] = true;
+                    s1 += s2;
+                    s2 += 2;
+                }
+            }
+
+            Console.WriteLine("The values of d <= {0} which can't be represented:", MAX);
+            for (int d = 1; d < MAX; d++) {
+                if (!found[d]) Console.Write("{0}  ", d);
+            }
+            Console.WriteLine();
+        }
+    }
+}