save project

my_search.py

@@ -7,4 +7,19 @@ 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
 # 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):
-    
+        low = 0
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+        high = len(alist)-1
+        while low <= high:
+            mid = (low+high)//2
+            guess = alist[mid]
+            if guess == num:
+                return mid 
+            elif guess < num:
+                low = mid+1
+            else:
+                high = mid-1    
+        return None
+result = binary_search(alist,num)
+print("老师说的数是",num)
+print("找到了，他在索引里的是",result)
+            
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