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]
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+num_list = [1, 3, 5, 8, 11, 15, 17, 18, 20, 21]
+guess = 0
+#low = 0
+def binary_search(alist,num):
+    low = 0
+    high = len(alist)+-1
+    #  = 20
+    while low  <= high :
+        mid = (low+high)//2
+        guess = alist[mid]
+        if guess == num :
+            #print("找到了")
+            return mid
+        elif guess < num :
+            low = mid + 1
+        else :
+            high = mid - 1
+    return None
+q = binary_search(num_list,20)     
+print(q)        
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