isPalindrome 풀이 추가

junzero741 · junzero741 · commit 0ea6ce851d08 · 2026-03-17T10:19:31.000+09:00
diff --git a/valid-palindrome/junzero741.ts b/valid-palindrome/junzero741.ts
@@ -0,0 +1,29 @@
+// TC: O(n)
+// SC: O(1)
+function isPalindrome(s: string): boolean {
+
+     let L = 0;
+     let R = s.length-1;
+    
+    while(R > 0 && L < s.length - 1 && L <= R) {
+        if(!isAlphanumeric(s[L])) {
+            L++;
+            continue;
+        }
+        if(!isAlphanumeric(s[R])) {
+            R--;
+            continue;
+        }
+        if(s[L].toLowerCase() !==  s[R].toLowerCase()) {
+            return false;
+        }
+        L++;
+        R--;
+    }
+
+    return true;
+};
+
+function isAlphanumeric(str: string): boolean {
+    return /^[a-zA-Z0-9]+$/.test(str);
+}
