1047. Remove All Adjacent Duplicates In String

Difficulty: Easy
98 / 98 test cases passed.
Runtime: 128 ms
Memory Usage: 13.7 MB

Easy/1047.RemoveAllAdjacentDuplicatesInString.py

@@ -0,0 +1,40 @@
+"""
+    Given a string S of lowercase letters, a duplicate removal consists of 
+    choosing two adjacent and equal letters, and removing them.
+    We repeatedly make duplicate removals on S until we no longer can.
+    Return the final string after all such duplicate removals have been made.
+    It is guaranteed the answer is unique.
+
+    Example:
+    Input: "abbaca"
+    Output: "ca"
+    Explanation: 
+    For example, in "abbaca" we could remove "bb" since the letters are 
+    adjacent and equal, and this is the only possible move.  The result of this 
+    move is that the string is "aaca", of which only "aa" is possible, so the 
+    final string is "ca".
+
+    Note:
+        1. 1 <= S.length <= 20000
+        2. S consists only of English lowercase letters.
+"""
+#Difficulty: Easy
+#98 / 98 test cases passed.
+#Runtime: 128 ms
+#Memory Usage: 13.7 MB
+
+#Runtime: 128 ms, faster than 25.09% of Python3 online submissions for Remove All Adjacent Duplicates In String.
+#Memory Usage: 13.7 MB, less than 98.64% of Python3 online submissions for Remove All Adjacent Duplicates In String.
+
+class Solution:
+    def removeDuplicates(self, S: str) -> str:
+        i = 0
+        while True:
+            if i + 1 > len(S) - 1:
+                break
+            if S[i] == S[i+1]:
+                S = S[:i] + S[i+2:]
+                i = max(i-1, 0)
+            else:
+                i += 1
+        return S