Added more

shichao-an · shichao-an · commit dd98c900890f · 2015-09-09T01:22:31.000-07:00
diff --git a/multiply_strings/solution.py b/multiply_strings/solution.py
@@ -0,0 +1,40 @@
+"""
+Given two numbers represented as strings, return multiplication of the numbers
+as a string.
+
+Note: The numbers can be arbitrarily large and are non-negative.
+"""
+
+
+class Solution(object):
+    def multiply(self, num1, num2):
+        """
+        :type num1: str
+        :type num2: str
+        :rtype: str
+        """
+        a = num1[::-1]
+        b = num2[::-1]
+        n = len(a)
+        m = len(b)
+        res = ['0' for i in range(n + m)]
+        for i in range(n):
+            c = 0
+            for j in range(m):
+                tmp = int(a[i]) * int(b[j]) + int(res[i + j]) + c
+                digit = tmp % 10
+                res[i + j] = str(digit)
+                c = tmp / 10
+            if c > 0:
+                res[m + i] = str(c)
+        res = ''.join(res[::-1])
+        for i, d in enumerate(res):
+            if d != '0':
+                return res[i:]
+        else:
+            return '0'
+
+s = Solution()
+
+print s.multiply('2', '21')
+print s.multiply('83', '3')
