Problem:
https://leetcode.com/problems/palindromic-substrings/description/
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:
|
1 2 3 |
Input: "abc" Output: 3 Explanation: Three palindromic strings: "a", "b", "c". |
Example 2:
|
1 2 3 |
Input: "aaa" Output: 6 Explanation: Six palindromic strings: "a", "a", "a", "aa", "aa", "aaa". |
Note:
- The input string length won’t exceed 1000.
Solution 1: Brute Force
Time complexity: O(n^2)
Space complexity: O(1)
C++
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 |
// Author: Huahua // Running time: 5 ms class Solution { public: int countSubstrings(string s) { int ans = 0; for (int i = 0; i < s.length(); ++i) { ans += count(s, i, i); // odd length ans += count(s, i, i + 1); // even length } return ans; } private: int count(const string& s, int l, int r) { int ans = 0; while (l >= 0 & r < s.length() && s[l--] == s[r++]) ++ans; return ans; } }; |
请尊重作者的劳动成果，转载请注明出处！花花保留对文章／视频的所有权利。
如果您喜欢这篇文章／视频，欢迎您捐赠花花。
If you like my articles / videos, donations are welcome.
Paypal
Venmo
huahualeetcode
huahualeetcode
微信打赏
Be First to Comment