2021-03-02

Author: JiayangWu

1544.整理字符串/1544-整理字符串.py

@@ -6,8 +6,9 @@ def makeGood(self, s):
         """
         stack = []
         for ch in s:
-            if not stack or abs(ord(stack[-1]) - ord(ch)) != 32:
+            if not stack or abs(ord(ch) - ord(stack[-1])) != 32:
                 stack.append(ch)
             else:
                 stack.pop()
-        return "".join(ch for ch in stack)
+
+        return "".join(stack)

1545.找出第N个二进制字符串中的第K位/1545-找出第N个二进制字符串中的第K位.py

@@ -5,21 +5,10 @@ def findKthBit(self, n, k):
         :type k: int
         :rtype: str
         """
-
-        def invert(s):
-            res = ""
-            for ch in s:
-                if ch == "0":
-                    res += "1"
-                else:
-                    res += "0"
-            return res
-
-        i = 1
+        # len 1， 3， 7， 15 ... L(n) = 2 * (L(n - 1)) + 1
+        # if k == 2 * (n - 2) + 2: return 1
         s = "0"
-        while i < n:
-            s = s + "1" + invert(s)[::-1]
-            i += 1
-            if k - 1 < len(s):
-                return s[k - 1]
-        return s[k - 1]
+        while len(s) <= k:
+            s = s + "1" + "".join([str(1 - int(ch)) for ch in s])[::-1]
+            # print (s)
+        return s[k - 1]