Runtime 233 ms (Top 71.99%) | Memory 21.0 MB (Top 5.67%)

Author: AnasImloul

scripts/algorithms/U/Unique Length-3 Palindromic Subsequences/Unique Length3 Palindromic Subsequences.py

@@ -0,0 +1,14 @@
+class Solution(object):
+    def countPalindromicSubsequence(self, s):
+        d=defaultdict(list)
+        for i,c in enumerate(s):
+            d[c].append(i)
+        ans=0
+        for el in d:
+            if len(d[el])<2:
+                continue
+            a=d[el][0]
+            b=d[el][-1]
+            ans+=len(set(s[a+1:b]))
+        return(ans)
+