diff --git a/solutions/375. Guess Number Higher or Lower II.md b/solutions/375. Guess Number Higher or Lower II.md
index 802c78f..a8db7bb 100644
--- a/solutions/375. Guess Number Higher or Lower II.md	
+++ b/solutions/375. Guess Number Higher or Lower II.md	
@@ -22,9 +22,11 @@ for all k in [i+1, j-1]:
 
 时间复杂度O(n^3), 空间复杂度O(n^2)。
 
-本题时间复杂度可优化至O(n^2)，可参考[1](https://artofproblemsolving.com/community/c296841h1273742)和[2](https://leetcode.com/problems/guess-number-higher-or-lower-ii/discuss/84823/Java-O(n2)-DP-solution-with-clear-explanation)。
+本题时间复杂度可优化至O(n^2)，可参考[1](https://artofproblemsolving.com/community/c296841h1273742)和[2](https://blog.csdn.net/Site1997/article/details/100168676)。
 亲测确实快一些，但是乍一看没怎么看懂，留个坑吧。
 
+> 注意：此题很容易错误地认为二分就是最优，但其实不是。二分只能保证猜测次数最小，而不是最坏情况下花费的钱最少。例如n=5，若采用二分，那么最坏情况下花费是3+4=7；但是实际上应该是4+2=6。
+
 # C++
 ``` C++
 class Solution {