save project

my_search.py

@@ -6,4 +6,18 @@ for i in range(1, 101):
 num = random.choice(alist)
 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):
\ No newline at end of file
+    low = 0
+    high = len(alist) - 1
+    while low <= high:
+        mid = (low + high) // 2
+        if num == alist[mid]:
+            return mid
+        elif mid < num:
+            low =mid + 1
+        else:
+            high=mid - 1
+    return None
+
+print("系统给的数是：",num)
+print("他在列表里的索引是：",binary_search(alist,num))
\ No newline at end of file