save project

my_search.py

@@ -7,3 +7,20 @@ 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):
+    # 使用二分查找法，找出9和20在列表里面的索引
+    a=0
+    b=len(alist)-1
+    while a<=b:
+        mid=(a+b)//2
+        if alist[mid] == num: # num_list[mid] == 9:
+            print("找到了")
+            break
+        elif b<a:
+            print("没有")
+            break
+        elif alist[mid]<num: # num_list[mid]<9:
+            a=mid+1
+        else:
+            b=mid-1
+    return None
+print(num,binary_search(alist,num))
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