diff --git a/src/string/125-valid-palindrome/index.js b/src/string/125-valid-palindrome/index.js
index c3d6195..04a37da 100644
--- a/src/string/125-valid-palindrome/index.js
+++ b/src/string/125-valid-palindrome/index.js
@@ -22,6 +22,8 @@
  * s consists only of printable ASCII characters.
  *
  * https://leetcode.com/problems/valid-palindrome/
+ *
+ * @related 680-valid-palindrome-ii
 */
 
 /**
@@ -32,10 +34,8 @@
  * 3. 指定空字符串为回文字符串
  *
  * 思路：
- * 1. 大小写统一，用 .toLowerCase 处理
- * 2. 正则匹配，筛选出由字母和数字所组成的字符串
- * 3. 字符串反转，.split + .reverse + .join 方法
- * 4. 将反转字符串与原字符串作比较得出结果
+ * 1. 统一大小写，正则匹配出字符串中的字母和数字，得到目标字符串
+ * 2. 将目标字符串反转，拿反转后的字符串与目标字符串作比较得出是否是回文字符串
  *
  * Time Complexity: O(n) = 遍历次数
  * Space Complexity: O(n) = 创建的数组长度 / 创建的字符串长度
diff --git a/src/string/125-valid-palindrome/optimize.js b/src/string/125-valid-palindrome/optimize.js
index 15b79ce..6051cd9 100644
--- a/src/string/125-valid-palindrome/optimize.js
+++ b/src/string/125-valid-palindrome/optimize.js
@@ -22,19 +22,19 @@
  * s consists only of printable ASCII characters.
  *
  * https://leetcode.com/problems/valid-palindrome/
+ *
+ * @related 680-valid-palindrome-ii
 */
 
 /**
  * 输入一个字符串，判断它是否是回文字符串
  * 注意：
- * 1. 只考虑字幕和数字
- * 2. 忽略字母的大小写
- * 3. 指定空字符串为回文字符串
+ * 1. 只考虑数字和字母，忽略字母的大小写
+ * 2. 定义空字符串为回文字符串
  *
  * 思路：
- * 1. 统一大小写，.toLowerCase
- * 2. 正则匹配筛选出字母和数字组成的字符串
- * 3. 遍历筛选后的字符串，利用 s[i] === s[len - i - 1] 来判断是否是回文字符串
+ * 1. 统一大小写，正则匹配出字符串中的字母和数字，得到目标字符串
+ * 2. 遍历目标字符串，判断 s[i] === s[s.length - i - 1] 来得出是否是回文字符串
  *
  * Time Complexity: O(n) = 遍历次数
  * Space Complexity: O(n) = 创建的字符串长度
diff --git a/src/string/125-valid-palindrome/optimize2.js b/src/string/125-valid-palindrome/optimize2.js
index 5d5bfbe..036fd2d 100644
--- a/src/string/125-valid-palindrome/optimize2.js
+++ b/src/string/125-valid-palindrome/optimize2.js
@@ -22,6 +22,8 @@
  * s consists only of printable ASCII characters.
  *
  * https://leetcode.com/problems/valid-palindrome/
+ *
+ * @related 680-valid-palindrome-ii
 */
 
 /**
@@ -34,8 +36,8 @@
  * 思路：
  * Two Pointers 双指针，原地做比较，不创建新的字符串、数组
  * 1. 创建 left right 两个下标，分别代表要比较的前后对称两个值的下标
- * 2. 遍历字符串 s，以此判断两个下标对应的值是否是字母或数字，如果不是则把对应下标向前/向后移动，直到为字母或数字值为止
- * 3. 依次判断 left right 对应的值
+ * 2. 遍历字符串 s，依次判断两个下标对应的值是否是字母或数字，如果不是则把对应下标向前/向后移动，直到值为字母或数字为止
+ * 3. 依次判断 s[left].toLowerCase === s[right].toLowerCase()
  *
  * Time Complexity: O(n) = 遍历次数
  * Space Complexity: O(1)
diff --git a/src/string/125-valid-palindrome/template-zh.js b/src/string/125-valid-palindrome/template-zh.js
index 82e493a..e516131 100644
--- a/src/string/125-valid-palindrome/template-zh.js
+++ b/src/string/125-valid-palindrome/template-zh.js
@@ -22,6 +22,8 @@
  * s consists only of printable ASCII characters.
  *
  * https://leetcode.cn/problems/valid-palindrome/
+ *
+ * @related 680-valid-palindrome-ii
 */
 
 module.exports = isPalindrome;
diff --git a/src/string/125-valid-palindrome/template.js b/src/string/125-valid-palindrome/template.js
index 39ee3a1..e15409b 100644
--- a/src/string/125-valid-palindrome/template.js
+++ b/src/string/125-valid-palindrome/template.js
@@ -22,6 +22,8 @@
  * s consists only of printable ASCII characters.
  *
  * https://leetcode.com/problems/valid-palindrome/
+ *
+ * @related 680-valid-palindrome-ii
 */
 
 module.exports = isPalindrome;
diff --git a/src/greedy/680-valid-palindrome-ii/index.js b/src/string/680-valid-palindrome-ii/index.js
similarity index 60%
rename from src/greedy/680-valid-palindrome-ii/index.js
rename to src/string/680-valid-palindrome-ii/index.js
index 17d178b..c0ef7ba 100644
--- a/src/greedy/680-valid-palindrome-ii/index.js
+++ b/src/string/680-valid-palindrome-ii/index.js
@@ -21,14 +21,24 @@
  * s consists of lowercase English letters.
  *
  * https://leetcode.com/problems/valid-palindrome-ii/
+ *
+ * @related 125-valid-palindrome
 */
 
+
 /**
- * Greedy Algorithm
+ * 给定一个非空字符串 s，最多删除一个字符，判断能否成为回文字符串
+ *
+ * 思路：
+ * 贪心算法 Greedy Algorithm
+ * 定义 left right 两个初始值为头尾的指针，依次判断 s[left] === s[right]
+ * 如果相同则 left += 1 right -= 1
+ * 如果不同则分别判断去除 s[left] 和 s[right] 后的子字符串是否是回文字符串
  *
- * Time Complexity: O(n) = while 循环次数 / isPalindrome 操作
- * Space complexity: O(n)
- * Auxiliary complexity: O(n)
+ * Time Complexity: O(n) = 遍历次数
+ * Space complexity: O(1)
+ * Auxiliary complexity: O(1)
+ * 其中 n 是字符串 s 的长度
  *
  * @param {string} s
  * @returns {boolean}
@@ -39,7 +49,7 @@ function validPalindrome(s) {
 
     while (left < right) {
         if (s[left] !== s[right]) {
-            return isPalindrome(s, left + 1, right) || isPalindrome(s, left, right - 1);
+            return isPalindrome(left + 1, right, s) || isPalindrome(left, right - 1, s);
         }
         left += 1;
         right -= 1;
@@ -49,16 +59,17 @@ function validPalindrome(s) {
 }
 
 /**
- * Time Complexity: O(n) = while 循环次数
+ * Time Complexity: O(n) = 遍历次数
  * Space complexity: O(1)
  * Auxiliary complexity: O(1)
+ * 其中 n 是字符串 s 的长度
  *
  * @param {string} s
  * @param {left} left
  * @param {right} right
  * @returns {boolean}
  */
-function isPalindrome(s, left, right) {
+function isPalindrome(left, right, s) {
     while (left < right) {
         if (s[left] !== s[right]) {
             return false;
diff --git a/src/greedy/680-valid-palindrome-ii/template-zh.js b/src/string/680-valid-palindrome-ii/template-zh.js
similarity index 93%
rename from src/greedy/680-valid-palindrome-ii/template-zh.js
rename to src/string/680-valid-palindrome-ii/template-zh.js
index 06b07a6..2f8ead2 100644
--- a/src/greedy/680-valid-palindrome-ii/template-zh.js
+++ b/src/string/680-valid-palindrome-ii/template-zh.js
@@ -21,6 +21,8 @@
  * s consists of lowercase English letters.
  *
  * https://leetcode.cn/problems/valid-palindrome-ii/
+ *
+ * @related 125-valid-palindrome
 */
 
 module.exports = validPalindrome;
diff --git a/src/greedy/680-valid-palindrome-ii/template.js b/src/string/680-valid-palindrome-ii/template.js
similarity index 93%
rename from src/greedy/680-valid-palindrome-ii/template.js
rename to src/string/680-valid-palindrome-ii/template.js
index 5ee1a14..50c5646 100644
--- a/src/greedy/680-valid-palindrome-ii/template.js
+++ b/src/string/680-valid-palindrome-ii/template.js
@@ -21,6 +21,8 @@
  * s consists of lowercase English letters.
  *
  * https://leetcode.com/problems/valid-palindrome-ii/
+ *
+ * @related 125-valid-palindrome
 */
 
 module.exports = validPalindrome;
diff --git a/src/greedy/680-valid-palindrome-ii/test.js b/src/string/680-valid-palindrome-ii/test.js
similarity index 100%
rename from src/greedy/680-valid-palindrome-ii/test.js
rename to src/string/680-valid-palindrome-ii/test.js