简体中文(ZH-CN) English(EN) 繁体中文(ZH-TW) 日本語(JA) 한국어(KO) Melayu(MS) Français(FR) Deutsch(DE)
Home > php教程 > php手册 > body text

php 二分查找法算法详解

WBOY
Release： 2016-06-13 09:27:35
Original
1389 people have browsed it

php 二分查找法算法详解

一、概念：二分查找又称折半查找，优点是比较次数少，查找速度快，平均性能好；其缺点是要求待查表为有序表，且插入删除困难。因此，折半查找方法适用于不经常变动而查找频繁的有序列表。首先，假设表中元素是按升序排列，将表中间位置记录的关键字与查找关键字比较，如果两者相等，则查找成功；否则利用中间位置记录将表分成前、后两个子表，如果中间位置记录的关键字大于查找关键字，则进一步查找前一子表，否则进一步查找后一子表。重复以上过程，直到找到满足条件的记录，使查找成功，或直到子表不存在为止，此时查找不成功。

二、代码：对于无序数组用以下方法即可。

header("Content-type:text/html;charset='utf-8'");
function twosearchmethod($arr,$val,$left,$right){
	if($left>$right){
		echo "找不到该数值";
		return ;
	}
	$middle=round(($left+$right)/2);
	if($arr[$middle]>$val){
		twosearchmethod($arr, $val, $left, $middle-1);
	}elseif($arr[$middle]<$val){
		twosearchmethod($arr, $val, $middle+1, $right);
	}else{
		echo $middle;
	}
	
}
$arr=array(1,9,3,4,5,6,7);
sort($arr);
print_r($arr);
echo "<br/>";
$val=1;
twosearchmethod($arr, $val, 0, 6);
Copy after login

Related labels：
algorithm
source：php.cn
Previous article：个性化自己的二维码，个性化自己二维码 Next article：PHP学习笔记（二） 了解PHP的基本语法以及目录结构，学习笔记基本语法
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Latest Issues
function_exists() cannot determine the custom function Function test () {return true;} if (function_exists ('test')) {echo "test is function...
From 2024-04-29 11:01:01
0
2
1429
The child window operates the parent window, but the output does not respond. The first two sentences are executable, but the last sentence cannot be implemented.
From 2024-04-19 15:37:47
0
1
1361
The page suddenly cannot pull css or bootstrap So I'm developing a page, I did part of it yesterday and it worked great, and today I cont...
From 2024-04-06 21:58:04
0
1
800
How to trigger render (with filter and pagination) on sort method in React? Here is my Sort.js style component: <SortWrapper><SortText>SortBy</SortText...
From 2024-04-06 21:28:37
0
1
2257
Sudoku checker not working? Can anyone help me identify the error? I tried everything on the online editor but still get the error. But when I do this on VSC...
From 2024-04-06 21:21:07
0
1
474
Related Topics
More>
Popular Recommendations
Popular Tutorials
More>
Related Tutorials
Popular Recommendations
Latest courses
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template
About us Disclaimer Sitemap
php.cn：Public welfare online PHP training，Help PHP learners grow quickly！