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my_search.py

@@ -6,4 +6,17 @@ 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):
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+def binary_search(alist,num):
+    low=0
+    high=len(alist)-1
+    while low<=high:
+        mid=(low+high)//2
+        if num == alist[mid]:
+            return mid
+            break
+        elif num < alist[mid]:
+            high = mid -1
+        else:
+            low = mid + 1
+    return None
+print(binary_search(alist,num))
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