valid-palindrome solution

Author: togo26

valid-palindrome/togo26.js

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+/**
+ * @param {string} s
+ * @return {boolean}
+ */
+// TC: O(n) / SC: O(n)
+var isPalindrome = function (s) {
+  const processed = s.toLowerCase().replaceAll(/[^a-z0-9]+/g, '');
+  const reversed = [...processed].reverse().join('');
+  return processed === reversed;
+};
+
+// TC: O(n) / SC: O(1)
+// With two pointers
+var isPalindrome = function (s) {
+  const nonAlphanumeric = new RegExp(/[^a-zA-Z0-9]+/);
+  let left = 0;
+  let right = s.length - 1;
+
+  while (left < right) {
+    while (left < right && nonAlphanumeric.test(s[left])) left++; // 단일 문자 테스트 O(1) 상수 취급
+    while (left < right && nonAlphanumeric.test(s[right])) right--;
+    if (s[left].toLowerCase() !== s[right].toLowerCase()) return false;
+    left++;
+    right--;
+  }
+
+  return true;
+};