save project

binary_search.py

 # 使用二分查找法，找出9和20在列表里面的索引
 # 使用二分查找法，找出9和20在列表里面的索引
 num_list = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
 num_list = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
-lxy = 0
-dsq = len(num_list) - 1
-while True:
+def binary_search(alist,num):
+    lxy = 0
+    dsq = len(alist) - 1
+    while True:
         mid = (lxy + dsq) // 2 
         mid = (lxy + dsq) // 2 
-    guess = num_list[mid]
-    if guess == 20:
-        print("找到了")
-        break
+        guess = alist[mid]
+        if guess == num:
+            return mid
         elif dsq < lxy:
         elif dsq < lxy:
             print("没有这个内容")
             print("没有这个内容")
             break
             break
-    elif guess < 20:
+        elif guess < num:
             lxy = mid + 1
             lxy = mid + 1
         else:
         else:
             dsq = mid - 1
             dsq = mid - 1