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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]
+
+#要查找的数
+goal1 = 9
+goal2 = 20
+low = 0
+high = len(num_list)-1
+while low<=high:
+    mid = (low+high)//2
+    num = num_list[mid]
+    if num == goal1:
+        print("索引:",mid)
+        break
+    
+    elif num<goal1:
+        low = mid+1
+    else:
+        high = mid-1   
+
+ 
+

defin.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]
+'''
+#要查找的数
+goal1 = 9
+goal2 = 20
+low = 0
+high = len(num_list)-1
+while low<=high:
+    mid = (low+high)//2
+    num = num_list[mid]
+    if num == goal1:
+        print("索引:",mid)
+        break
+    
+    elif num<goal1:
+        low = mid+1
+    else:
+        high = mid-1   
+
+'''
+
+def erfen(alist,number):
+    low = 0
+    high = len(alist)-1
+    while low<=high:
+        mid = (low+high)//2
+        num = alist[mid]
+        if num == number:
+            print("索引:",mid)
+            return mid
+            #break
+        
+        elif num<number:
+            low = mid+1
+        else:
+            high = mid-1   
+    return None
+res = erfen(num_list,2)
+print(res)

hexin.py

+#主要逻辑
+mid = (low+high)//2
+if 中间值 == 查找对象:
+    找到了
+elif 中间值<查找对象:
+    low = mid+1
+else:
+    high = mid-1
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t.py

+'''
+#主要逻辑
+mid = (low+high)//2
+if 中间值==查找对象:
+    找到了
+elif 中间值<查找对象:
+    low = mid+1
+else:
+    high = mid-1
+'''
+
+# 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]
+goal = 20
+low = 0
+high = len(num_list)-1
+while low<=high:
+    mid = (low+high)//2
+    num = num_list[mid]
+    if num==goal:
+        print("索引",mid)
+        break
+    elif num<goal:
+        low = mid+1
+    else:
+        high = mid-1
+
+

test.py

+'''
+题目：
+有一个无序的序列list_c = [37, 99, 73, 48, 47, 40, 40, 25, 99, 51], 请先排序并打印输出。
+分别尝试插入[20，40，41，100]到序列中合适的位置，保证其有序。
+'''
+list_c = [37, 99, 73, 48, 47, 40, 40, 25, 99, 51,99]
+list_s = [20, 40, 41, 100]
+#先排序
+order_list = sorted(list_c)
+print(order_list)
+#浅复制,保留原来数据
+ret = order_list[:]
+def insert_sort(ret,num):
+    low = 0                    #索引起点
+    high = len(ret)            #索引终点
+    while low<high:           # 起点索引大于或等于列表最后一个元素的索引，条件无法进入。
+        mid = (low+high)//2    # 取列表中间点的索引
+        if num<ret[mid]:       #  条件判断，如果待插入列表的值小于有序列表对应mid索引的值，就向左查询
+            high = mid-1         # 同时确认这个中间点mid索引就是ret列表的high最高索引
+        else:                  # 如果待插入列表的值大于有序列表对应mid索引的值，就向右查询，求中点
+            low = mid+1        # 同时确认这个中间点mid索引就是ret列表的开始索引low的值。
+    return low                 # 这个开始索引low就是最终计算出来的待插入索引的位置low，所以返回low
+for num in list_s:             # 循环去取待插入列表的元素。
+    index = insert_sort(ret,num)# 调用上面的函数取出插入元素索引值
+    ret.insert(index,num)      # 就地插入对应索引的值到列表ret中.
+print(ret)                     # 打印插入元素后的列表
+
+