参考第5题h，一下子就ac掉了，这里有个解释

不过和第五题思想一样啦

public int countSubstrings(String s) {        int count = 0;        for (int i = 0; i <2*s.length()-1; i++) {            int left = i/2;            int right = i/2;            if(i%2==1){                right++;            }            count+=getSub(s, left, right);        }        return count;    }    public int getSub(String s,int left,int right){        int count = 0;        while(left>=0&&right<=s.length()-1&&s.charAt(left)==s.charAt(right)){            left--;            right++;            count++;        }        return count;    }