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
-num_list = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
\ No newline at end of file
+num_list = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
+def er(list, shu):
+    low = 0
+    hige = len(list) - 1
+    while low <= hige:
+        mid = int((low + hige) // 2)
+        guess = list[mid]
+        if guess == shu:
+            return mid
+        if guess > shu:
+            hige = mid - 1
+        else:
+            low = mid + 1
+    return None
+num = int(input(""))
+print(er(num_list, num))