二分查找法 二分法代码c语言

传递热情，播撒知识，共享精彩，留下美好印记！

亲爱的学习者们，欢迎来到LearningYard学苑的天地。

今日，我们将一起探索“算法之海中的一段旅程——二分查找法”，诚邀您的加入。

一、认识二分查找

二分查找，又称为折半查找，是一种在有序数组中高效定位特定元素的方法。通过不断逼近目标的中值，锁定目标值的下标，其独特的检索方式让数据查找更加快捷简便。

Binary search, as it's also known, is an efficient algorithm for searching for a specific element in a sorted array. It narrows down the search by focusing on the middle value until the target value is found. This unique method of retrieval makes data searches more convenient and quicker.

二、效果对比

为了便于大家理解，我们附上了一张图。图中上方展示的是二分查找的过程，下方则是遍历查找的方式。虽然计算机的运行速度极快，但在比较中，从数组中取出下标对应的值需要相对较长的时间。从操作步骤上看，二分查找仅需三步即可完成，而遍历查找则需要十一步。

We've included a graphic to help illustrate the difference. Above is a representation of binary search, while below is the process of traversal search. While a computer's speed is impressive, in this comparison, accessing values from an array takes longer. In terms of steps, binary search is completed in just three steps, while traversal search takes eleven.

三、实现方法

在力扣平台中，编号为704的题目就是关于二分查找的实践题目。

We'll be working on a binary search function within the Solution class. This function takes an integer array and a target value. The core of binary search lies in the median value, which is determined by the interval between left and right values. This initial range is typically the entire array.

By continually narrowing the range of values being considered, we move the median closer to the target value. Inside the loop, with each iteration, we are either reducing the left or right values to narrow the search. This mid-value modification should be done at the beginning of each iteration.

在二分查找过程中，当找不到目标值时，我们就会退出循环并返回-1作为未找到的标识。即使最后的区间只剩下了一个元素并且这个元素并非目标值，也说明我们已经完全搜索过所有可能的范围。

Once the binary search is complete and no target value is found, we exit the loop and return -1 as a marker of non-existence. Even if the final range contains only one element that is not the target, it indicates that we have searched all possible ranges.

经过实践验证，该算法轻松通过测试。

After testing, it's confirmed that this algorithm works easily.

今天的分享就到这里了。如果您对文章内容有更多想法或建议，欢迎与我们分享交流。

Looking forward to hearing your thoughts and feedback on this article. See you all next time! Stay happy and enjoy your day!

排版：Dongyang