leetcode 43

python

Author: kyle8998

README.md

@@ -10,7 +10,7 @@ Personal Practice Set - Doing One a Day (sometimes) in a Variety of Languages (M
 
 |  # | Difficulty | Problem                                                                                      | Solution                                                          |
 | -- | ---------- | -------------------------------------------------------------------------------------------- | ----------------------------------------------------------------- |
-| 1  | Easy       | [Two Sum](leetcode/1-Easy-Two-Sum/problem.md)                                                | [Java](leetcode/1-Easy-Two-Sum/answer.java), [Ruby](leetcode/1-Easy-Two-Sum/answer.rb)|
+| 1  | Easy       | [Two Sum](leetcode/1-Easy-Two-Sum/problem.md)                                                | [Java](leetcode/1-Easy-Two-Sum/answer.java), [Python](leetcode/1-Easy-Two-Sum/answer.py), [Ruby](leetcode/1-Easy-Two-Sum/answer.rb)|
 | 2  | Medium     | [Add Two Numbers](leetcode/2-Medium-Add-Two-Numbers/problem.md)                              | [C](leetcode/2-Medium-Add-Two-Numbers/answer.c)                   |
 | 3  | Medium     | [Longest Substring Without Repeating Characters](leetcode/3-Medium-Longest-Substring-Without-Repeating-Characters/problem.md) | [Python](leetcode/3-Medium-Longest-Substring-Without-Repeating-Characters/answer.py) |
 | 4  | Hard       | [Median of Two Sorted Arrays](leetcode/4-Hard-Median-Of-Two-Sorted-Arrays/problem.md)        | [Python](leetcode/4-Hard-Median-Of-Two-Sorted-Arrays/answer.py)   |
@@ -22,7 +22,7 @@ Personal Practice Set - Doing One a Day (sometimes) in a Variety of Languages (M
 | 10 | Hard       | [Regular Expression Matching](leetcode/10-Hard-Regular-Expression-Matching/problem.md)       | [Python](leetcode/10-Hard-Regular-Expression-Matching/answer.py)  |
 | 11 | Medium     | [Container With Most Water](leetcode/11-Medium-Container-With-Most-Water/problem.md)         | [Python](leetcode/11-Medium-Container-With-Most-Water/answer.py)  |
 | 12 | Medium     | [Integer to Roman](leetcode/12-Medium-Integer-To-Roman/problem.md)                           | [Python](leetcode/12-Medium-Integer-To-Roman/answer.py)           |
-| 13 | Easy       | [Roman to Integer](leetcode/13-Easy-Roman-To-Integer/problem.md)                             | [C](leetcode/13-Easy-Roman-To-Integer/answer.c)                   |
+| 13 | Easy       | [Roman to Integer](leetcode/13-Easy-Roman-To-Integer/problem.md)                             | [C](leetcode/13-Easy-Roman-To-Integer/answer.c), [Python](leetcode/13-Easy-Roman-To-Integer/answer.py)|
 | 14 | Easy       | [Longest Common Prefix](leetcode/14-Easy-Longest-Common-Prefix/problem.md)                   | [Python](leetcode/14-Easy-Longest-Common-Prefix/answer.py)        |
 | 15 | Medium     | [3Sum](leetcode/15-Medium-3Sum/problem.md)                                                   | [Python](leetcode/15-Medium-3Sum/answer.py)                       |
 | 16 | Medium     | [3Sum Closest](leetcode/16-Medium-3Sum-Closest/problem.md)                                   | [Python](leetcode/16-Medium-3Sum-Closest/answer.py)               |
@@ -46,6 +46,7 @@ Personal Practice Set - Doing One a Day (sometimes) in a Variety of Languages (M
 | 39 | Medium     | [Combination Sum](leetcode/39-Medium-Combination-Sum/problem.md)                             | [Python](leetcode/39-Medium-Combination-Sum/answer.py)            |
 | 40 | Medium     | [Combination Sum II](leetcode/40-Medium-Combination-Sum-II/problem.md)                       | [Python](leetcode/40-Medium-Combination-Sum-II/answer.py)         |
 | 42 | Hard       | [Trapping Rain Water](leetcode/42-Hard-Trapping-Rain-Water/problem.md)                       | [Python](leetcode/42-Hard-Trapping-Rain-Water/answer.py)          |
+| 43 | Medium     | [Multiply Strings](leetcode/43-Medium-Multiply-Strings/problem.md)                           | [Python](leetcode/43-Medium-Multiply-Strings/answer.py)           |
 | 44 | Hard       | [Wildcard Matching](leetcode/44-Hard-Wildcard-Matching/problem.md)                           | [Python](leetcode/44-Hard-Wildcard-Matching/answer.py)            |
 | 46 | Medium     | [Permutations](leetcode/46-Medium-Permutations/problem.md)                                   | [Python](leetcode/46-Medium-Permutations/answer.py)               |
 | 47 | Medium     | [Permutations II](leetcode/47-Medium-Permutations-II/problem.md)                             | [Python](leetcode/47-Medium-Permutations-II/answer.py)            |

leetcode/1-Easy-Two-Sum/answer.py

@@ -0,0 +1,19 @@
+#!/usr/bin/python3
+
+#-------------------------------------------------------------------------------
+
+class Solution:
+    def twoSum(self, nums, target):
+        """
+        :type nums: List[int]
+        :type target: int
+        :rtype: List[int]
+        """
+        need = {}
+        for i in range(len(nums)):
+            if nums[i] in need:
+                return [need[nums[i]], i]
+            else:
+                need[target-nums[i]] = i
+        
+#-------------------------------------------------------------------------------

leetcode/13-Easy-Roman-To-Integer/answer.py

@@ -0,0 +1,41 @@
+#!/usr/bin/python3
+
+#------------------------------------------------------------------------------
+
+class Solution:
+    def romanToInt(self, s):
+        """
+        :type s: str
+        :rtype: int
+        """
+        result = 0
+        for i in range(len(s)):
+            if s[i] =='M':
+                result += 1000
+            elif s[i] == 'D':
+                result += 500
+            elif s[i] == 'C':
+                if (i+1) < len(s) and (s[i+1] == 'D' or s[i+1] == 'M'):
+                    result -= 100
+                else:
+                    result += 100
+            elif s[i] == 'L':
+                result += 50
+            elif s[i] == 'X':
+                if (i+1) < len(s) and (s[i+1] == 'C' or s[i+1] == 'L'):
+                    result -= 10
+                else:
+                    result += 10
+            elif s[i] == 'V':
+                result += 5
+            elif s[i] == "I":
+                if (i+1) < len(s) and (s[i+1] == 'X' or s[i+1] == 'V'):
+                    result -= 1
+                else:
+                    result += 1
+        
+        return result
+
+#------------------------------------------------------------------------------
+#Testing
+

leetcode/43-Medium-Multiply-Strings/answer.py

@@ -0,0 +1,34 @@
+#!/usr/bin/python3
+
+#------------------------------------------------------------------------------
+
+class Solution(object):
+    def multiply(self, num1, num2):
+        """
+        :type num1: str
+        :type num2: str
+        :rtype: str
+        """
+        if num1 == "0" or num2 == "0":
+            return "0"
+        
+        # Our products list must have a leading 0 because a product may carry over
+        products = [0]*(len(num1)+len(num2))
+        for i in range(len(num1)-1, -1, -1):
+            for j in range(len(num2)-1, -1, -1):
+                products[i+j+1] += int(num2[j])*int(num1[i])
+                
+        # Calculate each digit and each carry
+        carry = 0
+        for i in range(len(products)-1, -1, -1):
+            products[i], carry = (products[i] + carry) % 10, (products[i] + carry) // 10
+        
+        # Just put the digits in a string!
+        result = ""
+        for digit in products:
+            result += str(digit)
+            
+        return result.lstrip("0")
+
+#------------------------------------------------------------------------------
+#Testing

leetcode/43-Medium-Multiply-Strings/problem.md

@@ -0,0 +1,28 @@
+# Problem 43: Multiply Strings
+
+#### Difficulty: Medium
+
+#### Problem
+
+Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string.
+
+**Note:**
+
+1. The length of both num1 and num2 is < 110.
+2. Both num1 and num2 contain only digits 0-9.
+3. Both num1 and num2 do not contain any leading zero, except the number 0 itself.
+4. You must not use any built-in BigInteger library or convert the inputs to integer directly.
+
+#### Example
+
+<pre>
+Example 1:
+
+Input: num1 = "2", num2 = "3"
+Output: "6"
+
+Example 2:
+
+Input: num1 = "123", num2 = "456"
+Output: "56088"
+</pre>