diff --git a/leetcode-docs/hard/10-is-match.mdx b/leetcode-docs/hard/10-is-match.mdx
index 7745a156..c8008a93 100644
--- a/leetcode-docs/hard/10-is-match.mdx
+++ b/leetcode-docs/hard/10-is-match.mdx
@@ -111,7 +111,7 @@ var isMatch = function (s, p) {
   for (let i = 1; i <= m; i++) {
     for (let j = 1; j <= n; j++) {
       // 字母匹配上了, 或者 p 此时为 . 可能任意匹配, 状态从前一个转移过来即可
-      if (p[j - 1] === s[i - 1] || p[j - 1] === '.') {
+      if (s[i - 1] === p[j - 1] || p[j - 1] === '.') {
         dp[i][j] = dp[i - 1][j - 1]
         // 如果遇到 *, 需要关注 * 前面那个
       } else if (p[j - 1] === '*') {
diff --git a/leetcode-docs/hard/25-reverse-k-group.mdx b/leetcode-docs/hard/25-reverse-k-group.mdx
index 6c400351..097ff73c 100644
--- a/leetcode-docs/hard/25-reverse-k-group.mdx
+++ b/leetcode-docs/hard/25-reverse-k-group.mdx
@@ -83,15 +83,14 @@ var reverseKGroup = function (head, k) {
  * @return {ListNode}
  */
 var reverse = function (a, b) {
-  let prev = null,
-    head = a
+  let prev = null
 
   // 在 a, b 区间翻转
-  while (head !== b) {
-    const temp = head.next
-    head.next = prev
-    prev = head
-    head = temp
+  while (a !== b) {
+    const tmp = a.next
+    a.next = prev
+    prev = a
+    a = tmp
   }
 
   return prev
diff --git a/leetcode-docs/hard/30-find-substring.mdx b/leetcode-docs/hard/30-find-substring.mdx
index 3b5de442..c9ca2506 100644
--- a/leetcode-docs/hard/30-find-substring.mdx
+++ b/leetcode-docs/hard/30-find-substring.mdx
@@ -15,7 +15,7 @@ sidebar_label: 30. 串联所有单词的子串
 
 :::note 提示:
 
-- `1 <= s.length <= 104`
+- `1 <= s.length <= 10⁴`
 - `1 <= words.length <= 5000`
 - `1 <= words[i].length <= 30`
 - `words[i]` 和 `s` 由小写英文字母组成
@@ -94,7 +94,7 @@ var findSubstring = function (s, words) {
 
     // 声明一个新的哈希表 subMap, 记录 subStr 中每 w 个小字符串
     const subMap = new Map()
-    for (let j = 0; j < n * w; i += w) {
+    for (let j = 0; j < n * w; j += w) {
       const sub = subStr.slice(j, j + w)
 
       // 如果 words 中都没有子字符串, 可以提前终止