Fix flake8 related issues

Python/01-matrix.py

@@ -35,6 +35,11 @@
 
 import collections
 
+try:
+    xrange          # Python 2
+except NameError:
+    xrange = range  # Python 3
+
 
 class Solution(object):
     def updateMatrix(self, matrix):

Python/1-bit-and-2-bit-characters.py

@@ -1,32 +1,40 @@
 # Time:  O(n)
 # Space: O(1)
 
-# We have two special characters. The first character can be represented by one bit 0.
+# We have two special characters. The first character can be represented
+# by one bit 0.
 # The second character can be represented by two bits (10 or 11).
 #
-# Now given a string represented by several bits. Return whether the last character must
+# Now given a string represented by several bits.
+#  Return whether the last character must
 # be a one-bit character or not. The given string will always end with a zero.
 #
 # Example 1:
-# Input: 
+# Input:
 # bits = [1, 0, 0]
 # Output: True
-# Explanation: 
+# Explanation:
 # The only way to decode it is two-bit character and one-bit character.
 # So the last character is one-bit character.
 #
 # Example 2:
-# Input: 
+# Input:
 # bits = [1, 1, 1, 0]
 # Output: False
-# Explanation: 
+# Explanation:
 # The only way to decode it is two-bit character and two-bit character.
 # So the last character is NOT one-bit character.
 # Note:
 #
 # 1 <= len(bits) <= 1000.
 # bits[i] is always 0 or 1.
 
+try:
+    xrange          # Python 2
+except NameError:
+    xrange = range  # Python 3
+
+
 class Solution(object):
     def isOneBitCharacter(self, bits):
         """

Python/132-pattern.py

@@ -27,6 +27,12 @@
 #
 # Explanation: There are three 132 patterns in the sequence: [-1, 3, 2], [-1, 3, 0] and [-1, 2, 0].
 
+try:
+    xrange          # Python 2
+except NameError:
+    xrange = range  # Python 3
+
+
 class Solution(object):
     def find132pattern(self, nums):
         """

Python/2-keys-keyboard.py

@@ -4,10 +4,12 @@
 # Initially on a notepad only one character 'A' is present.
 # You can perform two operations on this notepad for each step:
 #
-# Copy All: You can copy all the characters present on the notepad (partial copy is not allowed).
+# Copy All: You can copy all the characters present on the notepad
+# (partial copy is not allowed).
 # Paste: You can paste the characters which are copied last time.
 # Given a number n.
-# You have to get exactly n 'A' on the notepad by performing the minimum number of steps permitted.
+# You have to get exactly n 'A' on the notepad by performing the minimum
+#  number of steps permitted.
 # Output the minimum number of steps to get n 'A'.
 #
 # Example 1:
@@ -21,6 +23,7 @@
 # Note:
 # The n will be in the range [1, 1000].
 
+
 class Solution(object):
     def minSteps(self, n):
         """

Python/24-game.py

@@ -14,11 +14,21 @@
 # Note:
 # The division operator / represents real division, not integer division.
 # For example, 4 / (1 - 2/3) = 12.
-# Every operation done is between two numbers. In particular, we cannot use - as a unary operator.
-# For example, with [1, 1, 1, 1] as input, the expression -1 - 1 - 1 - 1 is not allowed.
-# You cannot concatenate numbers together. For example, if the input is [1, 2, 1, 2], we cannot write this as 12 + 12.
+# Every operation done is between two numbers. In particular,
+# we cannot use - as a unary operator.
+# For example, with [1, 1, 1, 1] as input,
+# the expression -1 - 1 - 1 - 1 is not allowed.
+# You cannot concatenate numbers together. For example,
+# if the input is [1, 2, 1, 2], we cannot write this as 12 + 12.
 
 from operator import add, sub, mul, truediv
+from fractions import Fraction
+
+try:
+    xrange          # Python 2
+except NameError:
+    xrange = range  # Python 3
+
 
 class Solution(object):
     def judgePoint24(self, nums):
@@ -47,9 +57,6 @@ def judgePoint24(self, nums):
 
 # Time:  O(n^3 * 4^n) = O(1), n = 4
 # Space: O(n^2) = O(1)
-from fractions import Fraction
-from operator import add, sub, mul, div
-
 class Solution2(object):
     def judgePoint24(self, nums):
         """
@@ -59,15 +66,16 @@ def judgePoint24(self, nums):
         def dfs(nums):
             if len(nums) == 1:
                 return nums[0] == 24
-            ops = [add, sub, mul, div]
+            ops = [add, sub, mul, truediv]
             for i in xrange(len(nums)):
                 for j in xrange(len(nums)):
                     if i == j:
                         continue
-                    next_nums = [nums[k] for k in xrange(len(nums)) if i != k != j]
+                    next_nums = [nums[k] for k in xrange(len(nums))
+                                 if i != k != j]
                     for op in ops:
                         if ((op is add or op is mul) and j > i) or \
-                           (op == div and nums[j] == 0):
+                           (op == truediv and nums[j] == 0):
                             continue
                         next_nums.append(op(nums[i], nums[j]))
                         if dfs(next_nums):

Python/3sum-closest.py

@@ -1,9 +1,10 @@
 # Time:  O(n^2)
 # Space: O(1)
-#
-# Given an array S of n integers, 
-# find three integers in S such that the sum is closest to a given number, target. 
-# Return the sum of the three integers. 
+
+# Given an array S of n integers,
+# find three integers in S such that the sum is closest to a given number,
+# target.
+# Return the sum of the three integers.
 # You may assume that each input would have exactly one solution.
 #
 # For example, given array S = {-1 2 1 -4}, and target = 1.
@@ -36,6 +37,7 @@ def threeSumClosest(self, nums, target):
             i += 1
         return result
 
+
 if __name__ == '__main__':
     result = Solution().threeSumClosest([-1, 2, 1, -4], 1)
-    print result
+    print(result)

Python/3sum-smaller.py

@@ -1,6 +1,7 @@
 # Time:  O(n^2)
 # Space: O(1)
 
+
 class Solution:
     # @param {integer[]} nums
     # @param {integer} target

Python/3sum.py

@@ -13,6 +13,7 @@
 #    A solution set is:
 #    (-1, 0, 1)
 #    (-1, -1, 2)
+
 import collections
 
 

Python/4-keys-keyboard.py

@@ -1,20 +1,28 @@
 # Time:  O(1)
 # Space: O(1)
 
+try:
+    xrange          # Python 2
+except NameError:
+    xrange = range  # Python 3
+
+
 class Solution(object):
     def maxA(self, N):
         """
         :type N: int
         :rtype: int
         """
-        if N < 7: return N
-        if N == 10: return 20  # the following rule doesn't hold when N = 10
+        if N < 7:
+            return N
+        if N == 10:
+            return 20  # the following rule doesn't hold when N = 10
 
-        n  = N // 5 + 1  # n3 + n4 increases one every 5 keys 
+        n = N // 5 + 1  # n3 + n4 increases one every 5 keys
         # (1) n     =     n3 +     n4
         # (2) N + 1 = 4 * n3 + 5 * n4
         #     5 x (1) - (2) => 5*n - N - 1 = n3
-        n3 = 5*n - N - 1  
+        n3 = 5*n - N - 1
         n4 = n - n3
         return 3**n3 * 4**n4
 
@@ -27,9 +35,9 @@ def maxA(self, N):
         :type N: int
         :rtype: int
         """
-        if N < 7: return N
+        if N < 7:
+            return N
         dp = range(N+1)
         for i in xrange(7, N+1):
             dp[i % 6] = max(dp[(i-4) % 6]*3, dp[(i-5) % 6]*4)
         return dp[N % 6]
-

Python/4sum-ii.py

@@ -5,8 +5,10 @@
 # compute how many tuples (i, j, k, l) there are
 # such that A[i] + B[j] + C[k] + D[l] is zero.
 #
-# To make problem a bit easier, all A, B, C, D have same length of N where 0 <= N <= 500.
-# All integers are in the range of -228 to 228 - 1 and the result is guaranteed to be at most 231 - 1.
+# To make problem a bit easier, all A, B, C, D have same length of N
+# where 0 <= N <= 500.
+# All integers are in the range of -228 to 228 - 1 and the result
+# is guaranteed to be at most 231 - 1.
 #
 # Example:
 #

Python/4sum.py

@@ -6,7 +6,8 @@
 # Find all unique quadruplets in the array which gives the sum of target.
 #
 # Note:
-# Elements in a quadruplet (a,b,c,d) must be in non-descending order. (ie, a <= b <= c <= d)
+# Elements in a quadruplet (a,b,c,d) must be in non-descending order.
+# (ie, a <= b <= c <= d)
 # The solution set must not contain duplicate quadruplets.
 # For example, given array S = {1 0 -1 0 -2 2}, and target = 0.
 #
@@ -18,6 +19,11 @@
 
 import collections
 
+try:
+    xrange          # Python 2
+except NameError:
+    xrange = range  # Python 3
+
 
 # Two pointer solution. (1356ms)
 class Solution(object):
@@ -104,9 +110,10 @@ def fourSum(self, nums, target):
         for i in lookup.keys():
             if target - i in lookup:
                 for x in lookup[i]:
-                    for y in lookup[target -i]:
+                    for y in lookup[target - i]:
                         [a, b], [c, d] = x, y
-                        if a is not c and a is not d and b is not c and b is not d:
+                        if a is not c and a is not d and \
+                           b is not c and b is not d:
                             quad = sorted([nums[a], nums[b], nums[c], nums[d]])
                             if quad not in result:
                                 result.append(quad)
@@ -115,4 +122,4 @@ def fourSum(self, nums, target):
 
 if __name__ == '__main__':
     result = Solution().fourSum([1, 0, -1, 0, -2, 2], 0)
-    print result
+    print(result)