auto save

binary_search.py

+import random
 # 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, 34, 56, 65, 67, 78, 90]
+num = random.choice(num_list)  # 查找的数字
+
+def binary_search(num_list, num):
+    low = 0  # 最低的索引
+    high = len(num_list)-1  # 最高的索引
+    while low <= high:  # 当最低索引小于等于最高索引的时候查找
+        mid = (low+high)//2  # 计算中间索引值
+        guess = num_list[mid]  # 通过中间索引取到列表中对应的数字  猜测的数值
+        if guess == num:  # 判断猜测的数字如果等于查找的数字
+            return mid
+        elif guess < num:  # 如果猜测的数字小于查找的数字
+            low = mid + 1  # 让最低索引移到中间索引的右边
+        else:  # 如果猜测的数字大于查找的数字
+            high = mid - 1  # 让最高索引移到中间索引的左边
+    return None
+
+result = binary_search(num_list, num)
+print('要查找的数字是', num)
+print('它的索引是', result)

demo1.py

+import random
+# 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]
+num = random.choice(num_list)
+def binary_search(num_list,num):
+    low = 0
+    high = len(num_list)-1
+    while low <= high:
+        mid = (low+high) // 2
+        guess = num_list[mid]
+        if guess == num:
+            return mid
+        if guess < num:
+            low = mid + 1
+        else:
+            high = mid-1
+    return None
+
+
+result = binary_search(num_list,num)
+print(num)
+print(result)
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