feat: palindromic substrings

Author: minji-go

palindromic-substrings/minji-go.java

@@ -0,0 +1,27 @@
+/*
+    Problem: https://leetcode.com/problems/palindromic-substrings/
+    Description: return the number of palindromic substrings in it.
+    Concept: Two Pointers, String, Dynamic Programming
+    Time Complexity: O(N²), Runtime 6ms
+    Space Complexity: O(1), Memory 41.62MB
+*/
+class Solution {
+    public int countSubstrings(String s) {
+        int totalCount = 0;
+        for(int i=0; i<s.length(); i++){
+            totalCount+= countPalindromes(s, i, i);
+            totalCount+= countPalindromes(s, i, i+1);
+        }
+        return totalCount;
+    }
+
+    public int countPalindromes(String s, int left, int right){
+        int count = 0;
+        while(left>=0 && right<s.length() && s.charAt(left)==s.charAt(right)) {
+            count++;
+            right++;
+            left--;
+        }
+        return count;
+    }
+}