Adding 0647 Palindromic Substrings

LeetCode/0647_Palindromic_Substrings.py

@@ -0,0 +1,21 @@
+class Solution:
+ def countSubstrings(self, s: str) -> int:
+ N = len(s)
+ # declaring a DP matrix of size nxn
+ dp = [[0 for i in range(N)] for j in range(N)]
+ # looping through substring of every size and checking whether it is a valid substring
+ for l in range(N):
+ for i in range(N-l):
+ if l == 0:
+ dp[i][i] = 1
+ continue
+ if s[i] == s[i+l]:
+ if l == 1:
+ dp[i][i+l] = 1
+ elif dp[i+1][i+l-1] == 1:
+ dp[i][i+l] = 1
+ count = 0
+ for i in range(N):
+ for j in range(N):
+ count+=dp[i][j]
+ return count