【leetcode】1316. Distinct Echo Substrings

题目如下：

Return the number of distinct non-empty substrings of text that can be written as the concatenation of some string with itself.

Example 1:

Input: text = "abcabcabc"
Output: 3
Explanation: The 3 substrings are "abcabc", "bcabca" and "cabcab".

Example 2:

Input: text = "leetcodeleetcode"
Output: 2
Explanation: The 2 substrings are "ee" and "leetcodeleetcode".

Constraints:

• 1 <= text.length <= 2000
• text has only lowercase English letters.

解题思路：这个题目还真是奇葩，我一开始以为是找出符合 (xxx) * n 这样格式的子串，没想到却是(xxx) * 2格式，这个格式的意思就是，一个字符串分成前后两部分，两部分的值是一样的。因为text.length<=2000，所以直接暴力计算吧。

代码如下：

class Solution(object):
    def distinctEchoSubstrings(self, text):
        """
        :type text: str
        :rtype: int
        """
        res = 0
        dic = {}
        # dp = [[0]* len(text) for _ in text]
        for i in range(len(text)):
            for j in range(i + 1, len(text)):
                if (j - i + 1) % 2 != 0:
                    continue
                mid = (i+j) / 2
                #print text[i:mid],text[mid:j+1]
                v1 = text[i:mid+1]
                v2 = text[mid+1:j+1]
                if v1 == v2 and v1 not in dic:
                    #print v1,v2
                    res += 1
                    dic[v1] = 1
        return res