auto save

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]
\ No newline at end of file
+
+def binary_search(alist,num):
+    low = 0         # 初始最低索引
+    high = len(alist)-1          # 初始最高索引
+    while low <= high:      # 当最低索引小于等于最高索引
+        mid = (low + high) // 2
+        guess = alist[mid]
+        if guess == num:        # 中间值等于查找对象，返回索引
+            return mid
+        elif guess < num:       # 中间值小于查找对象
+            low = mid + 1
+        else:                   # 中间值大于查找对象
+            high = mid - 1
+    return None
+a = binary_search(num_list,11)
+print(a)
\ No newline at end of file