valid palindrome solution

robinyoon-dev · robinyoon-dev · commit 262fd2376f30 · 2026-03-16T14:12:20.000+09:00
diff --git a/valid-palindrome/robinyoon-dev.js b/valid-palindrome/robinyoon-dev.js
@@ -0,0 +1,52 @@
+/**
+ * @param {string} s
+ * @return {boolean}
+ */
+var isPalindrome = function (s) {
+
+    //NOTE: 다음에는 투 포인터 방식으로 불어보겠습니다...
+
+    //0. 엣지케이스 대비: 빈칸인 경우.
+    if (s.trim() === '') {
+        return true;
+    }
+
+    //1. s를 array로 변환
+    const sArray = Array.from(s);
+
+    // 알파벳만 남기는 작업 
+    // (Alphanumeric characters include letters and numbers.)
+    const aAscii = 'a'.charCodeAt(0);
+    const zAscii = 'z'.charCodeAt(0);
+    const aUpperAscii = 'A'.charCodeAt(0);
+    const zUpperAscii = 'Z'.charCodeAt(0);
+    const zeroAscii = '0'.charCodeAt(0);
+    const nineAscii = '9'.charCodeAt(0);
+
+    const filteredArray = [];
+    for (let char of sArray) {
+        let charAscii = char.charCodeAt(0);
+
+        let isCharacter = (charAscii >= aAscii && charAscii <= zAscii) || (charAscii >= aUpperAscii && charAscii <= zUpperAscii) || (charAscii >= zeroAscii && charAscii <= nineAscii);
+
+        if (isCharacter) {
+            filteredArray.push(char);
+        }
+    }
+
+    // 대문자 -> 소문자로 변경하는 작업
+    const lowerArray = [];
+    for (let char of filteredArray) {
+        lowerArray.push(char.toLowerCase());
+    }
+
+    // reverse 해도 똑같은지 확인하는 작업
+    const reversedArray = [...lowerArray].reverse();
+
+    const originalString = lowerArray.join();
+    const reversedString = reversedArray.join();
+
+    return originalString === reversedString;
+
+};
+
