745 · 回文的范围

class Solution {
public:
    /**
     * @param l: A positive integer
     * @param r: A positive integer
     * @return:  the number of interesting subranges of [L,R]
     */
    int palindromicRanges(int l, int r) {
        // test
        int count = 0;
        int len = r - l + 1 + 1;
        int record[len] = {0};
        for(int i = 1; i <= len -1;i++){
            record[i] = record[i - 1] + 
                is_palindromic(l + i - 1);
        }

        for(int left = l;left <= r;left++){
            for(int right = left;right <= r;right++){
                int tmp = 0;
                tmp = record[right - l + 1] - record[left - l + 1 - 1];
                if((tmp % 2) == 0){
                    count++;
                }
            }
        }

        return record[2];

        return count;
    }

    bool is_palindromic(int number){
        string str;
        str = to_string(number);
        int start = 0;
        int end = str.size()-1;
        while(start < end){
            if(str[start] == str[end]){
                start += 1;
                end += 1;
            }else{
                return false;
            }
        }
        return true;
    }
};