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]
+alist = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
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+# 设置主要参数                       
+num = 20      # 要查找的数：20
+
+
+
+
+def a(alist,num):
+    low=0
+    high=len(alist)-1
+    while low <= high:
+        mid = (low+high) // 2 #取中间的索引位置   //取整
+        guess_num = alist[mid]   # 猜测的数值
+        if guess_num == num:
+            return mid#立马退出当前循环，然后执行循环外的代码
+        elif guess_num < num:
+            low = mid+1
+        elif guess_num > num:
+            high = mid-1
+    return None
+result=a(alist,num)
+print(num)
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