diff --git a/my_search.py b/my_search.py
index 1996c12..70ea7d6 100644
--- a/my_search.py
+++ b/my_search.py
@@ -5,5 +5,19 @@ for i in range(1, 101):
     alist.append(i)
 num = random.choice(alist)
 # 请完善二分查找函数binary_search(),查找出num在列表alist里面的索引位置
-def binary_search(alist,num)
-def binary_search(alist,num):
\ No newline at end of file
+def binary_search(alist,num):
+    low=0
+    high=len(alist)-1
+    while low <= high:
+        mid = (low+high) // 2
+        guess_num = alist[mid]
+        if guess_num ==num:
+            return mid
+        elif guess_num<num:
+            low=mid+1
+        elif guess_num>num:
+            high=mid-1
+    return None
+    result=binary_search(alist,num)
+    print("数：",num)
+    print("索引：",result)
\ No newline at end of file