save project

my_search.py

@@ -6,4 +6,21 @@ 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_num = alist[mid]
+        if guess_num == num:
+            return mid
+        elif guess_num < 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：",result)
+