two pointer

two_pointer/Valid_Palindrome_II.py

@@ -1,11 +1,12 @@
 # https://leetcode.com/problems/valid-palindrome-ii/
 def valid_palindrome(s):
     start, end = 0, len(s) - 1
-    left = left_delete(start,end)
-    right = right_delete(start,end)
+    left = left_delete(start, end)
+    right = right_delete(start, end)
     return left or right
 
-def left_delete(start,end):
+
+def left_delete(start, end):
     c = 0
     while start <= end:
         if c > 1:
@@ -18,14 +19,15 @@ def left_delete(start,end):
             end -= 1
     return True
 
-def right_delete(start,end):
+
+def right_delete(start, end):
     c = 0
     while start <= end:
         if c > 1:
             return False
         if s[start] != s[end]:
             c += 1
-            end-= 1
+            end -= 1
         else:
             start += 1
             end -= 1
@@ -36,4 +38,4 @@ def right_delete(start,end):
 # s = "abca"
 s = "tebbem"
 # s = "cbbcc"
-print(valid_palindrome(s))
+print(valid_palindrome(s))

two_pointer/linkListcycle.py

@@ -26,15 +26,15 @@ def cycle_check(self, head):
             if fast == slow:
                 return True
         return False
-    
+
     def cycle_check_medium(self, head):
         s = set()
         temp = head
         c = 0
         while temp:
             if temp in s:
                 return f"tail connects to node index {c}"
-            c+=1
+            c += 1
             s.add(temp)
             temp = temp.next
         return "no cycle"
@@ -66,7 +66,7 @@ def append_to_tail(self, val):
             self.head = node
         else:
             current_node = self.head
-            while current_node.next != None:
+            while current_node.next is not None:
                 current_node = current_node.next
             current_node.next = node
         return self.head

two_pointer/reverse_array.py

@@ -1,11 +1,12 @@
 # reverse array in place
 def reverse(nums):
-    start, end = 0, len(nums)-1
+    start, end = 0, len(nums) - 1
     while start < end:
-        nums[start],nums[end] = nums[end],nums[start]
-        start+=1
-        end-= 1
+        nums[start], nums[end] = nums[end], nums[start]
+        start += 1
+        end -= 1
     return nums
 
-nums = [1,2,3,4,5]
-print(reverse(nums))
+
+nums = [1, 2, 3, 4, 5]
+print(reverse(nums))

two_pointer/reverse_string.py

@@ -1,11 +1,12 @@
-
 def reverse_string(s):
-    start, end = 0,len(s)-1
+    start, end = 0, len(s) - 1
 
     while start < end:
-        s[start],s[end] = s[end],s[start]
-        start+=1
+        s[start], s[end] = s[end], s[start]
+        start += 1
         end -= 1
     return s
-s = ["h","e","l","l","o"]
-print(reverse_string(s))
+
+
+s = ["h", "e", "l", "l", "o"]
+print(reverse_string(s))

two_pointer/reverse_string_II.py

@@ -1,25 +1,26 @@
 # https://leetcode.com/problems/reverse-string-ii/
 
-def reverse_II(s,k):
+def reverse_II(s, k):
     if k > len(s):
         return s
     if len(s) == k:
         return s[::-1]
-    start,end = 0,len(s)-1
+    start, end = 0, len(s) - 1
     s = list(s)
     while start < end:
-        st, en = start,(start+k)-1
-        print("==",st,en,len(s[st:en]))
+        st, en = start, (start + k) - 1
+        print("==", st, en, len(s[st:en]))
         while st < en:
-            print("before",s[st],s[en])
-            s[st],s[en] = s[en],s[st]
+            print("before", s[st], s[en])
+            s[st], s[en] = s[en], s[st]
             print("after", s[st], s[en])
-            st+=1
-            en-=1
-        print(start,start+k)
-        start += 2*k
+            st += 1
+            en -= 1
+        print(start, start + k)
+        start += 2 * k
     return "".join(s)
 
+
 # s = "abcdefg"
 # k = 8
 # s = "abcd"
@@ -28,4 +29,4 @@ def reverse_II(s,k):
 # k = 3
 s = "hyzqyljrnigxvdtneasepfahmtyhlohwxmkqcdfehybknvdmfrfvtbsovjbdhevlfxpdaovjgunjqlimjkfnqcqnajmebeddqsgl"
 k = 39
-print(reverse_II(s,k))
+print(reverse_II(s, k))

two_pointer/sorted_square.py

@@ -7,7 +7,7 @@ def square_sorted(nums):
     start, end = 0, n-1
     res = [0]*n
     index = n-1
-    while end >=0 and start >= 0:
+    while end >= 0 and start >= 0:
         if abs(nums[start]) > abs(nums[end]):
             res[index] = nums[start]*nums[start]
             start += 1

two_pointer/valid_palindrome.py

@@ -1,15 +1,16 @@
 # 
 
-def valid_palindrom(s):
+def valid_palindrome(s):
     s = s.lower()
     arr = [x for x in s if x.isalnum()]
     start, end = 0, len(arr) - 1
     while start < end:
         if arr[start].isalnum() and arr[end].isalnum():
             if arr[start].lower() != arr[end].lower():
                 return False
-        start+=1
-        end-=1
+        start += 1
+        end -= 1
     return True
 
-print(valid_palindrom("A man, a plan, a canal: Panama"))
+
+print(valid_palindrome("A man, a plan, a canal: Panama"))