Commit a58f140

committed

647. Palindromic Substrings

1 parent 473916a commit a58f140Copy full SHA for a58f140

File tree

+55

-0

lines changed

+55

-0

lines changed

Lines changed: 30 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,30 @@`
	`1`	+/// The time complexity of the `countSubstrings` function is `O(n^2)`,
	`2`	+/// where `n` is the length of the input string `s`. This is because we
	`3`	+/// loop over each character in `s` and call the `countPalindromes`
	`4`	`+/// function twice for each character.`
	`5`	+/// The space complexity of the countSubstrings function is `O(1)`
	`6`	`+`
	`7`	`+class Solution {`
	`8`	`+ int countSubstrings(String s) {`
	`9`	`+ int count = 0;`
	`10`	`+ for (int i = 0; i < s.length; i++) {`
	`11`	`+ count += countPalindromes(s, i, i); // odd-length palindromes`
	`12`	`+ count += countPalindromes(s, i, i + 1); // even-length palindromes`
	`13`	`+ }`
	`14`	`+ return count;`
	`15`	`+ }`
	`16`	`+`
	`17`	`+ int countPalindromes(String s, int left, int right) {`
	`18`	`+ int count = 0;`
	`19`	`+ while (left >= 0 && right < s.length && s[left] == s[right]) {`
	`20`	`+ count++;`
	`21`	`+ left--;`
	`22`	`+ right++;`
	`23`	`+ }`
	`24`	`+ return count;`
	`25`	`+ }`
	`26`	`+}`
	`27`	`+`
	`28`	`+void main(List<String> args) {`
	`29`	`+ print(Solution().countSubstrings('aaa'));`
	`30`	`+}`

Lines changed: 25 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,25 @@`
	`1`	`+647. Palindromic Substrings`
	`2`	`+https://leetcode.com/problems/palindromic-substrings/`
	`3`	`+`
	`4`	`+Given a string s, return the number of palindromic substrings in it.`
	`5`	`+A string is a palindrome when it reads the same backward as forward.`
	`6`	`+A substring is a contiguous sequence of characters within the string.`
	`7`	`+`
	`8`	`+`
	`9`	`+Example 1:`
	`10`	`+`
	`11`	`+Input: s = "abc"`
	`12`	`+Output: 3`
	`13`	`+Explanation: Three palindromic strings: "a", "b", "c".`
	`14`	`+`
	`15`	`+Example 2:`
	`16`	`+`
	`17`	`+Input: s = "aaa"`
	`18`	`+Output: 6`
	`19`	`+Explanation: Six palindromic strings: "a", "a", "a", "aa", "aa", "aaa".`
	`20`	`+`
	`21`	`+`
	`22`	`+Constraints:`
	`23`	`+`
	`24`	`+1 <= s.length <= 1000`
	`25`	`+s consists of lowercase English letters.`

Comments

(0)