Time: 3 ms (67.2%), Space: 17.7 MB (73.86%) - LeetHub

Author: hogan-tech

0316-remove-duplicate-letters/0316-remove-duplicate-letters.py

@@ -0,0 +1,22 @@
+# time complexity: O(n)
+# space complexity: O(n)
+class Solution:
+    def removeDuplicateLetters(self, s: str) -> str:
+        stack = []
+        seen = set()
+        lastCharIdx = {c: i for i, c in enumerate(s)}
+
+        for i, c in enumerate(s):
+            if c not in seen:
+                while stack and c < stack[-1] and i < lastCharIdx[stack[-1]]:
+                    seen.discard(stack.pop())
+                seen.add(c)
+                stack.append(c)
+
+        return ''.join(stack)
+
+
+s = "bcabc"
+print(Solution().removeDuplicateLetters(s))
+s = "cbacdcbc"
+print(Solution().removeDuplicateLetters(s))