diff --git a/content/posts/leetcode.md b/content/posts/leetcode.md
index fb00ca5..480de0a 100644
--- a/content/posts/leetcode.md
+++ b/content/posts/leetcode.md
@@ -207,3 +207,61 @@ func isEvenOddTree(root *TreeNode) bool {
 go语言中的for range循环, 如果使用类似`for key, value := range list` 的形式, 那么key, value这两个变量都会在当前作用域下新建, 意味着即使在前面定义了key, key的值在循环结束后也不会被修改. 若想修改之前定义的key值, 需要将value也提前定义好并使用`=`而不是`:=`.
 
 go语言中的for range循环时如果使用`:=`会新建两个变量, 然后将slice中的值复制给value变量, 将对应的index值赋值给key变量, 这意味着value变量不会指向数组中对应位置的地址, 而是一个不变的单独地址.
+
+## day4 2024-03-01
+
+### 2864. Maximum Odd Binary number
+
+You are given a binary string s that contains at least one '1'.
+
+You have to rearrange the bits in such a way that the resulting binary number is the maximum odd binary number that can be created from this combination.
+
+Return a string representing the maximum odd binary number that can be created from the given combination.
+
+Note that the resulting string can have leading zeros.
+
+Example 1:
+
+> Input: s = "010"
+> Output: "001"
+> Explanation: Because there is just one '1', it must be in the last position. So the answer is "001".
+
+Example 2:
+
+> Input: s = "0101"
+> Output: "1001"
+> Explanation: One of the '1's must be in the last position. The maximum number that can be made with the remaining digits is "100". So the answer is "1001".
+
+### 题解
+
+题目中说明了给出的字符串中至少有一个1, 因此可以复制一个字符串, 然后遍历原字符串, 遇到第一个1放在最后一位, 0永远插入到倒数第二位, 不是第一个1放在字符串最前面. 由此除保证字符串是奇数的最后一个1以外, 其余的1都在字符串最前面, 其余的0都插入在最前面的一串1和最后的1之间. 保证了字符串是最大的奇数字符串.
+
+### 代码
+
+```go
+func maximumOddBinaryNumber(s string) string {
+    s_copy := ""
+    flag := 0
+    for _, value := range s{
+        if value == '1'{
+            if flag != 0{
+                s_copy = "1" + s_copy
+            } else{
+                s_copy = s_copy + "1"
+                flag = 1
+            }
+        } else{
+            if(len(s_copy) >=2){
+                s_copy = string(s_copy[:len(s_copy)-1]) + "0" + string(s_copy[len(s_copy)-1])
+            } else {
+                s_copy = "0" + s_copy
+            }
+        }
+    }
+    return s_copy
+}
+```
+
+### 总结
+
+在处理字符串的时候像中间某个位置插入字符也要使用双引号, 如插入字符0要用`+"0"`而不是`+'0'`, 此外在截取切片的时候go的切片是左闭右开的. 如[0:3]截取的是0,1,2三个数