解题思路:
(1)中心扩展法
class Solution {
public:
int helper(string &s,int left,int right) {
int count=0;
while(left>=0 && right<s.length() && s[left]==s[right]) {
left--;
right++;
count++;
}
return count;
}
int countSubstrings(string s) {
int sum=0;
for(int i=0;i<s.length();i++) {
int a = helper(s,i,i);
int b = helper(s,i,i+1);
sum = sum+a;
sum = sum+b;
}
return sum;
}
};