diff --git "a/24.12/demo/\350\257\255\346\263\225\345\210\206\346\236\220.md" "b/24.12/\350\257\255\346\263\225\345\210\206\346\236\220.md"
similarity index 99%
rename from "24.12/demo/\350\257\255\346\263\225\345\210\206\346\236\220.md"
rename to "24.12/\350\257\255\346\263\225\345\210\206\346\236\220.md"
index 8d924599..104666c7 100644
--- "a/24.12/demo/\350\257\255\346\263\225\345\210\206\346\236\220.md"
+++ "b/24.12/\350\257\255\346\263\225\345\210\206\346\236\220.md"
@@ -402,7 +402,7 @@ function parseExpression(tokens, start, end, precedence, currentIndex = {index:
     var numNode = new NumberAstNode(tokens[start].value);
     var result = numNode;
 
-    while (currentIndex.index < end) {
+    while (currentIndex.index < end - 1) {
         var opNode = new InfixOperatorAstNode(tokens[currentIndex.index + 1]);
         if (opNode.precedence <= precedence) {
             currentIndex.index = start; // currentIndex是用对象类型，记录的上下文在所有的dfs中是一个单例
@@ -415,4 +415,5 @@ function parseExpression(tokens, start, end, precedence, currentIndex = {index:
     }
     return result;
 }
-```
\ No newline at end of file
+```
+这个代码行数不多，但是因为有循环和递归，所以比较难理解。
\ No newline at end of file