Palindromic Substrings

def countSubstrings(s):
    res = 0
    
    for i in range(len(s)):
        # odd length
        l = r = i
        while l >= 0 and r < len(s) and s[l] == s[r]:
            res += 1
            l -= 1
            r += 1
            
        # even length
        l = i
        r = i + 1
        while l >= 0 and r < len(s) and s[l] == s[r]:
            res += 1
            l -= 1
            r += 1
            
    return res