auto save

my_search.py

@@ -3,7 +3,26 @@ import random
 alist = []
 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):
\ No newline at end of file
+def binary_search(alist,num):
+    low=0
+    high=len(alist)-1
+    while low<=high:
+        mid=(low+high)//2
+        gusse=alist[mid]
+        if gusse==num:
+            return mid
+        elif gusse<num:
+            low =mid  + 1
+        else:
+            high=mid -1
+    return None
+
+result=binary_search(alist,num)
+print("老师给的数字是",num)
+print('它在列表里的索引是', result)
+