feat(cses): a few problems

kattis/18-2-2025/j.py

@@ -0,0 +1,17 @@
+s = input()
+n = len(s)
+last_occurrence = {}
+total = 0
+
+for right in range(n):
+    char = s[right]
+    left = last_occurrence.get(char, -1) + 1
+
+    unique_chars = set()
+    for l in range(right - 1, left - 1, -1):
+        if s[l] not in unique_chars:
+            total += 1
+        unique_chars.add(s[l])
+    last_occurrence[char] = right
+
+print(total)