Create minimum-number-of-swaps-to-make-the-binary-string-alternating.py

Author: kamyu104

Python/minimum-number-of-swaps-to-make-the-binary-string-alternating.py

@@ -0,0 +1,25 @@
+# Time:  O(n)
+# Space: O(1)
+
+class Solution(object):
+    def minSwaps(self, s):
+        """
+        :type s: str
+        :rtype: int
+        """
+        def cost(s, x): 
+            diff = 0 
+            for c in s:
+                diff += int(c) != x
+                x ^= 1
+            return diff//2
+    
+        ones = s.count('1')
+        zeros = len(s)-ones 
+        if abs(ones-zeros) > 1:
+            return -1
+        if ones > zeros:
+            return cost(s, 1)
+        if ones < zeros:
+            return cost(s, 0)
+        return min(cost(s, 1), cost(s, 0))