save project

diy2.py

-username = "python"
-userpassword = "123456"
-while True:
-    name = input("请输入用户名:")
-    password = input("请输入密码:")
-    if name == username and password == userpassword:
-        print("登录成功!")
-        break
-    if name != username:
-        print("用户名不存在,请重新输入!")
-        continue
-    if password != userpassword:
-        print("密码输入有误,请重新输入!")
-print("欢迎来到贝尔编程!")
+num_list = [1,3,5,8,11,15,17,18,20,21]
+
+
+def erfen(num_list,num):
+    low = 0
+    high = len(num_list)-1
+    if num not in num_list:
+        print('在列表中找不到数据:' + str(num))
+        exit()
+    while low != high:
+        mid = (low+high)//2
+        nnum = num_list[mid]
+        if nnum == num:
+            return mid
\ No newline at end of file
+        elif nnum < num :
+            low = mid+1
+        elif nnum > num :
+            high = mid-1
+    return None
\ No newline at end of file