class Solution:
def countSubstrings(self, s: str) -> int:
res = 0
for i in range(len(s)):
res += self.traversal(s, i, i)
res += self.traversal(s, i, i+1)
return res
def traversal(self, s, l, r):
this_res = 0
while l >= 0 and r < len(s) and s[l] == s[r]:
this_res += 1
l -= 1
r += 1
return this_res