diff --git a/src/my_project/interviews/amazon_high_frequency_23/round_7/optimal_partition_string.py b/src/my_project/interviews/amazon_high_frequency_23/round_7/optimal_partition_string.py
new file mode 100644
index 00000000..3f2117d6
--- /dev/null
+++ b/src/my_project/interviews/amazon_high_frequency_23/round_7/optimal_partition_string.py
@@ -0,0 +1,18 @@
+class Solution:
+    def partitionString(self, s: str) -> int:
+
+        # 1-based positions: 0 means "character never seen"
+        last_pos = [0] * 26
+        partitions = 0
+        partition_start = 0
+
+        for i in range(len(s)):
+
+            # last occurrence falls inside the open partition -> must cut
+            if last_pos[ord(s[i]) - ord('a')] >= partition_start:
+                partitions += 1
+                partition_start = i + 1
+
+            last_pos[ord(s[i]) - ord('a')] = i + 1
+
+        return partitions
\ No newline at end of file