add 5-Longest-Palindromic-Substring

javascript/5-Longest-Palindromic-Substring.js

@@ -0,0 +1,34 @@
+function longestPalindrome(s) {
+  let res = "";
+  let resLen = 0;
+
+  for (let i = 0; i < s.length; i++) {
+    let l = i;
+    let r = i;
+
+    while (l >= 0 && r < s.length && s[l] === s[r]) {
+      if (r - l + 1 > resLen) {
+        res = s.slice(l, r + 1);
+        resLen = r - l + 1;
+      }
+
+      l -= 1;
+      r += 1;
+    }
+
+    l = i;
+    r = i + 1;
+
+    while (l >= 0 && r < s.length && s[l] === s[r]) {
+      if (r - l + 1 > resLen) {
+        res = s.slice(l, r + 1);
+        resLen = r - l + 1;
+      }
+
+      l -= 1;
+      r += 1;
+    }
+  }
+
+  return res;
+}