feat: Palindromic Substrings

Author: HodaeSsi

palindromic-substrings/HodaeSsi.py

@@ -0,0 +1,19 @@
+# space complexity: O(n^2)
+# time complexity: O(n^2) (*exactly, n^2 / 2)
+class Solution:
+	def countSubstrings(self, s: str) -> int:
+		dp = [[False] * len(s) for _ in range(len(s))] # dp[i][j] = True if s[i:j+1] is a palindrome
+		for i in range(len(s)):
+			for j in range(i, -1, -1):
+				if i == j:
+					dp[j][i] = True
+					continue
+				if i - j == 1:
+					dp[j][i] = s[i] == s[j]
+					continue
+				if s[i] == s[j]:
+						if dp[j+1][i-1]:
+							dp[j][i] = True
+		
+		return sum([sum(row) for row in dp])
+