Add solution for challenge #16

Author: Mauricio Klein

.gitignore

@@ -48,3 +48,6 @@ build-iPhoneSimulator/
 
 # unless supporting rvm < 1.11.0 or doing something fancy, ignore this:
 .rvmrc
+
+# Python
+**/*.pyc

challenge-16/Makefile

@@ -0,0 +1,4 @@
+test:
+	python test_*.py
+
+.PHONY: test

challenge-16/README.md

@@ -0,0 +1,15 @@
+# Add two numbers as a linked list
+
+This problem was asked by Microsoft.
+
+## Description
+
+You are given two linked-lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.
+
+## Example
+
+```
+Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
+Output: 7 -> 0 -> 8
+Explanation: 342 + 465 = 807.
+```

challenge-16/__init__.py

@@ -0,0 +1,25 @@
+class Solution:
+    def addTwoNumbers(self, l1, l2):
+        minSize = min(len(l1), len(l2))
+        out = []
+        carry = 0
+
+        for i in range(minSize):
+            sum = l1[i] + l2[i] + carry
+
+            if sum > 9:
+                out.append(sum-10)
+                carry = 1
+            else:
+                out.append(sum)
+                carry = 0
+
+        if len(l1) > minSize:
+            for i in range(minSize, len(l1)):
+                out.append(l1[i])
+
+        if len(l2) > minSize:
+            for i in range(minSize, len(l2)):
+                out.append(l2[i])
+
+        return out

challenge-16/solver.py

@@ -0,0 +1,14 @@
+import unittest
+from solver import Solution
+
+class TestSolver(unittest.TestCase):
+    def test_solver(self):
+        self.assertEqual(Solution().addTwoNumbers([2,4,3  ], [5,6,4  ]), [7,0,8  ])
+        self.assertEqual(Solution().addTwoNumbers([2,4,3,1], [5,6,4  ]), [7,0,8,1])
+        self.assertEqual(Solution().addTwoNumbers([2,4,3  ], [5,6,4,1]), [7,0,8,1])
+        self.assertEqual(Solution().addTwoNumbers([1,2,3  ], [       ]), [1,2,3  ])
+        self.assertEqual(Solution().addTwoNumbers([       ], [1,2,3  ]), [1,2,3  ])
+        self.assertEqual(Solution().addTwoNumbers([       ], [       ]), [       ])
+
+if __name__ == "__main__":
+    unittest.main()