programming puzzles

Lisp/Puzzles/sum-squares-diff.lisp

@@ -0,0 +1,17 @@
+(defun sum-squares (s e)
+  (loop for x from s to e
+     sum (expt x 2)))
+
+(defun square-sum (s e)
+  (expt (loop for x from s to e
+           sum x) 2))
+
+(defparameter *prs* '(11 7 5 3 2 1 ))
+
+
+(defun more-prs ()
+  (loop for x from (+ 2 (car *prs*)) by 2
+     until (>= (length *prs*) 10002)
+     do
+       (unless (divisors x)
+         (push x *prs*))))

Ruby/Codility/Lesson-4/max-product-of-three.rb

@@ -0,0 +1,18 @@
+def solution(a)
+  n = a.size
+  res = -1000 ^ 3
+  for p in 0 .. (n-3)
+    for q in (p+1) .. (n-2)
+      for r in (q+1) .. (n-1)
+        if ((0 <= p) and (p < q) and (q < r) and (r < n))
+          v = (a[p] * a[q] * a[r])
+          res = v if v > res
+          #puts "p#{p}* q#{q}* r#{r}= #{a[p] * a[q] * a[r]} "
+        end
+      end
+    end
+  end
+  res
+end
+
+p solution [-3,1,2,-2,5,6]

Ruby/commas.rb

@@ -0,0 +1,14 @@
+def commas(num)
+  str=num.to_s.reverse
+  res = ''
+  for x in 0 .. (str.size-1)
+    res << str[x]
+    if (((x+1) % 3) == 0) and x < (str.size-1)
+      res << ','
+    end
+  end
+  res.reverse
+end
+
+p commas(1000000)
+p commas(999999)