save project

my_search.py

@@ -7,3 +7,17 @@ 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
+    high = len(alist)-1
+    while low<=high:
+        mid = (low+high)//2
+        
+        if alist[mid] == num:
+            return mid
+        elif alist[mid] < num:
+            low = mid +1
+        else:
+            high = mid - 1
+    return None
+print(binary_search(alist,29))
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