Add palindromic-substrings solution

Author: Jeehay28

palindromic-substrings/Jeehay28.js

@@ -0,0 +1,37 @@
+/**
+ * @param {string} s
+ * @return {number}
+ */
+
+// TC : O(n^2)
+// SC : O(1)
+
+var countSubstrings = function (s) {
+  // For each character in the string, treat it as the center of a potential palindrome.
+
+  // 'Count Palindromic Substrings' helper function
+  const countPS = (left, right) => {
+    let cnt = 0;
+    while (left >= 0 && right < s.length && s[left] === s[right]) {
+      cnt += 1;
+      left -= 1;
+      right += 1;
+    }
+    return cnt;
+  };
+
+  let totCnt = 0;
+
+  for (let i = 0; i < s.length; i++) {
+    // left === right : 1 center point, odd-length palindromic
+    totCnt += countPS(i, i);
+
+    // left !== right : 2 center points, even-length palindromic
+    totCnt += countPS(i, i + 1);
+  }
+
+  return totCnt;
+};
+
+
+