Data commit

Task/Spiral-matrix/Octave/spiral-matrix.octave

@@ -0,0 +1,21 @@
+function a = spiral(n)
+  a = ones(n*n, 1);
+  u = -(i = n) * (v = ones(n, 1));
+  for k = n-1:-1:1
+    j = 1:k;
+    a(j+i) = u(j) = -u(j);
+    a(j+(i+k)) = v(j) = -v(j);
+    i += 2*k;
+  endfor
+  a(cumsum(a)) = 1:n*n;
+  a = reshape(a, n, n)'-1;
+endfunction
+
+>> spiral(5)
+ans =
+
+    0    1    2    3    4
+   15   16   17   18    5
+   14   23   24   19    6
+   13   22   21   20    7
+   12   11   10    9    8