diff --git a/docs/dataStructures-algorithms/几道常见的子符串算法题.md b/docs/dataStructures-algorithms/几道常见的子符串算法题.md
index c85c1b74..cd2a3e31 100644
--- a/docs/dataStructures-algorithms/几道常见的子符串算法题.md
+++ b/docs/dataStructures-algorithms/几道常见的子符串算法题.md
@@ -459,7 +459,7 @@ public class Main {
         return 0;
       }
     }
-    return flag == 1 ? res : -res;
+   return flag != 2 ? res : -res;
 
   }