647. Palindromic Substrings 回文子串的数量

Posted 2020-10-02 Long Long Journey

Given a string, your task is to count how many palindromic substrings in this string.

The substrings with different start indexes or end indexes are counted as different substrings even they consist of same characters.

Example 1:

Input: "abc"
Output: 3
Explanation: Three palindromic strings: "a", "b", "c".

Example 2:

Input: "aaa"
Output: 6
Explanation: Six palindromic strings: "a", "a", "a", "aa", "aa", "aaa".

Note:

1. The input string length won‘t exceed 1000.

求回文子串的数量，每一个子串拥有不同的star index 和不同的end index

class Solution(object):
    def countSubstrings(self, s):
        """
        :type s: str
        :rtype: int
        """
        num = 0
        for i in range(0, len(s) + 1):
            for j in range(i + 1, len(s) + 1):
                sub = s[i:j]
                if(sub == sub[::-1]):
                    num = num + 1
        return num

来自为知笔记(Wiz)