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PalindromicSubstrings.java

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//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.

class PalindromicSubstrings {

int result = 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);

extendPalindrome(s, i, i + 1);

}

return result;

}

public void extendPalindrome(String s, int left, int right) {

while(left >= 0 && right < s.length() && s.charAt(left) == s.charAt(right)) {

result++;

left--;

right++;

}

}

}