auto save

my_search.py

@@ -6,4 +6,20 @@ for i in range(1, 101):
 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
+        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("老师给的数是：", num)
+print("它在列表里的索引是：", result) 
\ No newline at end of file