README.md

@@ -96,3 +96,6 @@ CFcSBwgCCBoHRhkKU1cGAA4AGU5YQR5THBwNFwoGGAxTQQMQVBUSBg4EAAwQRhUQVBUHFAQTGRpT QQM
 * Completed in: 37 mins, 56 secs.
 * Feedback
   > [elevator-maintenance] Sample output of the test cases in readme.txt for python language is not match with the return type. Changing first output from `0.1,1.1.1,1.2,1.2.1,1.11,2,2.0,2.0.0` to `["0.1", "1.1.1", "1.2", "1.2.1", "1.11", "2", "2.0", "2.0.0"]` and changing second output from `1.0,1.0.2,1.0.12,1.1.2,1.3.3` to `["1.0", "1.0.2", "1.0.12", "1.1.2", "1.3.3"]` would be great.
+
+### gearing-up-for-destruction
+* Completed in: 1 hr, 19 mins, 28 secs.

extra/gearing-up-for-destruction/solution.py

@@ -1,19 +1,20 @@
 def solution(pegs):
+    a, b = -1, -1
     odd, even = sum_odd_even(pegs)
 
     if len(pegs) % 2 == 0:
         s = 2 * odd - 2 * even - pegs[-1] + pegs[0]
-        if 2*s < 3:
-            return [-1, -1]
         if s % 3 == 0:
-            return [2*s/3, 1]
+            a, b = 2*s/3, 1
         else:
-            return [2*s, 3]
+            a, b = 2*s, 3
     else:
         s = 2 * odd - 2 * even + pegs[-1] + pegs[0]
-        if 2*s < 1:
-            return [-1, -1]
-        return [2*s, 1]
+        a, b = 2*s, 1
+
+    if check_all_gear_size(a, b, pegs):
+        return [a, b]
+    return [-1, -1]
 
 def sum_odd_even(pegs):
     odd, even = 0, 0
@@ -24,11 +25,32 @@ def sum_odd_even(pegs):
             even += peg
     return odd, even
 
+def check_all_gear_size(a, b, pegs):
+    if a < 2*b:
+        return False
+
+    p = list(pegs) if b == 1 else [b*p for p in pegs]
+
+    last_peg = p[0]
+    last_gear = a
+    for i in range(1, len(p)):
+        peg = p[i]
+        gap = peg - last_peg
+        if gap - last_gear < b:
+            return False
+        last_gear = gap - last_gear
+        last_peg = peg
+
+    return True
+
 
 tests = [
         ([4, 30, 50], [12, 1]),
         ([4, 17, 50], [-1, -1]),
         ([1, 2], [-1, -1]),
+        ([1, 3], [-1, -1]),
+        ([1, 4], [2, 1]),
+        ([1, 5], [8, 3]),
         ([1, 2, 3], [-1, -1]),
         ]