add: 回文数

src/math/palindrome-number.js

@@ -0,0 +1,16 @@
+/**
+ * @param {number} x
+ * @return {boolean}
+ */
+export const isPalindrome = function (x) {
+  if (x < 0 || (x % 10 === 0 && x !== 0)) return false // 如果末尾数为0且不是0
+
+  let reverse = 0
+
+  while (reverse < x) {
+    reverse = reverse * 10 + x % 10
+    x = x / 10 | 0
+  }
+
+  return reverse === x || (reverse / 10 | 0) === x
+}