Palindromic Substrings（C++回文子串）

問題解決のアイデア：

（1）中心拡大法

（2）同様のトピック：https：//blog.csdn.net/coolsunxu/article/details/114890560？ops_request_misc =％257B％2522request％255Fid％2522％253A％2522161611804316780269875340％2522％252C％2522scm％2522％253A％252220140713.130102334 .pc％255Fblog。％2522％257D＆request_id = 161611804316780269875340＆biz_id = 0＆utm_medium = distribution.pc_search_result.none-task-blog-2〜blog〜first_rank_v2〜rank_v29-1-114890560.pc_v2_rank_blog_default＆utm_term987％E5％E5％9

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;
    }
};