save project

my_search.py

@@ -6,4 +6,18 @@ for i in range(1, 101):
 num = random.choice(alist)
 # 请完善二分查找函数binary_search(),查找出num在列表alist里面的索引位置
 
-def binary_search(alist,num):
\ No newline at end of file
+def binary_search(alist,num):
+    low = 0
+    high = len(alist)-1#最后的索引
+    while low <=high:
+        mid = (low+high)//2#中间值 //整除
+        guess = alist[mid]#mid 所对应的值
+        if guess == num: #如果对上了
+            return mid
+        elif  guess >num:#如果假设的数大于猜的数，说明数在右边，把high左移的
+            high = mid-1
+        elif  guess <num:#如果假设的数小于猜的数，说明数在左边，把low右移的
+            low = mid+1
+result  = binary_search(alist,num)
+print('数是',num)
+print('索引：',result)