diff --git a/problems/0122.买卖股票的最佳时机II.md b/problems/0122.买卖股票的最佳时机II.md
index ff1b6d4a..29aa5b83 100644
--- a/problems/0122.买卖股票的最佳时机II.md
+++ b/problems/0122.买卖股票的最佳时机II.md
@@ -139,17 +139,11 @@ Java：
 // 贪心思路
 class Solution {
     public int maxProfit(int[] prices) {
-        int sum = 0;
-        int profit = 0;
-        int buy = prices[0];
+        int result = 0;
         for (int i = 1; i < prices.length; i++) {
-            profit = prices[i] - buy;
-            if (profit > 0) {
-                sum += profit;
-            }
-            buy = prices[i];
+            result += Math.max(prices[i] - prices[i - 1], 0);
         }
-        return sum;
+        return result;
     }
 }
 ```
diff --git a/problems/0455.分发饼干.md b/problems/0455.分发饼干.md
index b6fa4a98..1e1c4afe 100644
--- a/problems/0455.分发饼干.md
+++ b/problems/0455.分发饼干.md
@@ -117,6 +117,7 @@ public:
 Java：
 ```java
 class Solution {
+    // 思路1：优先考虑饼干，小饼干先喂饱小胃口
     public int findContentChildren(int[] g, int[] s) {
         Arrays.sort(g);
         Arrays.sort(s);
@@ -132,10 +133,30 @@ class Solution {
     }
 }
 ```
+```java
+class Solution {
+    // 思路2：优先考虑胃口，先喂饱大胃口
+    public int findContentChildren(int[] g, int[] s) {
+        Arrays.sort(g);
+        Arrays.sort(s);
+        int count = 0;
+        int start = s.length - 1;
+        // 遍历胃口
+        for (int index = g.length - 1; index >= 0; index--) {
+            if(start >= 0 && g[index] <= s[start]) {
+                start--;
+                count++;
+            }
+        }
+        return count;
+    }
+}
+```
 
 Python：
 ```python3
 class Solution:
+    # 思路1：优先考虑胃饼干
     def findContentChildren(self, g: List[int], s: List[int]) -> int:
         g.sort()
         s.sort()
@@ -145,6 +166,20 @@ class Solution:
                 res += 1
         return res
 ```
+```python
+class Solution:
+    # 思路2：优先考虑胃口
+    def findContentChildren(self, g: List[int], s: List[int]) -> int:
+        g.sort()
+        s.sort()
+        start, count = len(s) - 1, 0
+        for index in range(len(g) - 1, -1, -1): # 先喂饱大胃口
+            if start >= 0 and g[index] <= s[start]: 
+                start -= 1
+                count += 1
+        return count
+```
+
 Go：
 ```golang
 //排序后，局部最优
diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md
index 02713c65..914fba23 100644
--- a/problems/0541.反转字符串II.md
+++ b/problems/0541.反转字符串II.md
@@ -152,7 +152,35 @@ class Solution {
     }
 }
 ```
+```java
+// 解法3
+class Solution {
+    public String reverseStr(String s, int k) {
+        char[] ch = s.toCharArray();
+        // 1. 每隔 2k 个字符的前 k 个字符进行反转
+        for (int i = 0; i< ch.length; i += 2 * k) {
+            // 2. 剩余字符小于 2k 但大于或等于 k 个，则反转前 k 个字符
+            if (i + k <= ch.length) {
+                reverse(ch, i, i + k -1);
+                continue;
+            }
+            // 3. 剩余字符少于 k 个，则将剩余字符全部反转
+            reverse(ch, i, ch.length - 1);
+        }
+        return  new String(ch);
 
+    }
+    // 定义翻转函数
+    public void reverse(char[] ch, int i, int j) {
+    for (; i < j; i++, j--) {
+        char temp  = ch[i];
+        ch[i] = ch[j];
+        ch[j] = temp;
+    }
+
+    }
+}
+```
 Python：
 ```python
 class Solution: