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:
The input string length won't exceed 1000.
一刷
题解：
在字符串中遍历, 以当前index为中心点往外扩展。中心点为i(odd), 和中心点为i, i+1
class Solution {
int count = 0;
public int countSubstrings(String s) {
if(s == null || s.length() == 0) return 0;
for(int i=0; i<s.length(); i++){
extendPalindrome(s, i, i);// odd length
extendPalindrome(s, i, i+1);//even length
}
return count;
}
private void extendPalindrome(String s, int left, int right){
while(left>=0 && right<s.length() && s.charAt(left) == s.charAt(right)){
count++;
left--;
right++;
}
}
}
