PHP backtracking algorithm example sharing

小云云
Release: 2023-03-19 16:56:01
Original
1618 people have browsed it

This article mainly introduces the backtracking algorithm implemented in PHP, and analyzes the implementation steps and usage methods of the PHP backtracking algorithm in the form of specific examples, involving recursion, traversal, operation and other related operation skills of strings and arrays. Friends in need can refer to Next, I hope it can help everyone.

Question:

One big cow camel has 2 bags of rice, one medium cow camel has one bag of rice, and two small cow camels have one bag of rice Bags of rice. How many large cows, how many medium cows, and how many small cows are needed to make 100 bags of rice?

Implementation code:


##

<?php
/*
 * k = 2x + y + 1/2z
 取值范围
 * 0 <= x <= 1/2k
 * 0 <= y <= k
 * 0 <= z < = 2k
 * x,y,z最大值 2k
 */
$daMi = 100;
$result = array();
function isOk($t,$daMi,$result)
{/*{{{*/
 $total = 0;
 $hash = array();
 $hash[1] = 2;
 $hash[2] = 1;
 $hash[3] = 0.5;
 for($i=1;$i<=$t;$i++)
 {
 $total += $result[$i] * $hash[$i];
 }
 if( $total <= $daMi)
 {
 return true;
 }
 return false;
}/*}}}*/
function backtrack($t,$daMi,$result)
{/*{{{*/
 //递归出口
 if($t > 3)
 {
 //输出最优解
 if($daMi == (2 * $result[1] + $result[2] + 0.5 * $result[3]))
 {
  echo "最优解,大米:${daMi},大牛:$result[1],中牛: $result[2],小牛:$result[3]\n";
 }
 return;
 }
 for($i = 0;$i <= 2 * $daMi;$i++)
 {
 $result[$t] = $i;
 //剪枝
 if(isOk($t,$daMi,$result))
 {
  backtrack($t+1,$daMi,$result);
 }
 $result[$t] = 0;
 }
}/*}}}*/
backtrack(1,$daMi,$result);
?>
Copy after login

The running results are as follows:

Related recommendations:

php backtracking algorithm to solve the n-queens problem_PHP tutorial

##

The above is the detailed content of PHP backtracking algorithm example sharing. For more information, please follow other related articles on the PHP Chinese website!

Related labels:
source:php.cn
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
Popular Tutorials
More>
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!