Initial data commit

Task/Pythagorean-quadruples/D/pythagorean-quadruples.d

@@ -0,0 +1,43 @@
+import std.bitmanip : BitArray;
+import std.stdio;
+
+enum N = 2_200;
+enum N2 = 2*N*N;
+
+void main() {
+    BitArray found;
+    found.length = N+1;
+
+    BitArray aabb;
+    aabb.length = N2+1;
+
+    uint s=3;
+
+    for (uint a=1; a<=N; ++a) {
+        uint aa = a*a;
+        for (uint b=1; b<N; ++b) {
+            aabb[aa + b*b] = true;
+        }
+    }
+
+    for (uint c=1; c<=N; ++c) {
+        uint s1 = s;
+        s += 2;
+        uint s2 = s;
+        for (uint d=c+1; d<=N; ++d) {
+            if (aabb[s1]) {
+                found[d] = true;
+            }
+            s1 += s2;
+            s2 += 2;
+        }
+    }
+
+    writeln("The values of d <= ", N, " which can't be represented:");
+    for (uint d=1; d<=N; ++d) {
+        if (!found[d]) {
+            write(d, ' ');
+        }
+    }
+    writeln;
+}