


This article will summarize some good PHP sorting algorithms for you. I hope these algorithms will be helpful to all students.
The code is as follows | Copy code | ||||
1. Bubble algorithm, sorting algorithm, because in the sorting process, small numbers are always placed forward and large numbers are placed backward, which is equivalent to bubbles rising, so it is called bubble sort $array = array(a,f,c,b,e,h,j,i,g); function maopao_fun($array){ if($len return $arr; } $count = count($array); for($i=0;$i for($j=$count-1;$j>$i;$j--){ if($array[$j] > $array[$j-1]){ $tmp = $array[$j]; $array[$j] = $array[$j-1]; $array[$j-1] = $tmp; } } return $array; } 2. Quick sort, Quicksort is an improvement on bubble sort. Proposed by C. A. R. Hoare in 1962. Its basic idea is to divide the data to be sorted into two independent parts through one sorting pass. All the data in one part is smaller than all the data in the other part, and then the two parts of the data are quickly sorted in this way, The entire sorting process can be performed recursively, so that the entire data becomes an ordered sequence. function quickSort($arr){ $len = count($arr); if($len return $arr; } $key = $arr[0]; $left_arr = array(); $right_arr = array(); for($i=1; $i If($arr[$i] $left_arr[] = $arr[$i]; $right_arr[] = $arr[$i]; } } $left_arr = quickSort($left_arr); $right_arr = quickSort($right_arr); return array_merge($left_arr, array($key), $right_arr); } |
3.Select sort
Each pass selects the smallest (or largest) element from the data elements to be sorted,
The order is placed at the end of the sorted array until all data elements to be sorted are arranged. Selection sort is an unstable sorting method
The code is as follows | Copy code | ||||||||
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The code is as follows | Copy code |
function insert_sort($arr){ $count = count($arr); for($i=1; $i $tmp = $arr[$i]; $j = $i - 1; while($arr[$j] > $tmp){ $arr[$j+1] = $arr[$j]; $arr[$j] = $tmp; $j--; } } return $arr; } $arr = array(49,38,65,97,76,13,27); print_r(insert_sort($arr)); |
PHP implementation of four sorting algorithms
1) The basic idea of Insertion Sort is:
Each time a record to be sorted is inserted into the appropriate position in the previously sorted sub-file according to its key size, until all records are inserted.
2) The basic idea of Selection Sort is:
In each pass, the record with the smallest keyword is selected from the records to be sorted and placed at the end of the sorted sub-file until all records are sorted.
3) The basic idea of bubble sort is:
Compare the keywords of the records to be sorted pairwise, and if it is found that the order of the two records is reversed, they will be exchanged until there are no records in the reverse order.
4) Quick sort is essentially the same as bubble sort, and is an application of exchange sort. So the basic idea is the same as the bubble sort above.
代码如下 | 复制代码 |
/** return array_merge($left_arr, array($key), $right_arr); /*End of file sort.php*/ |

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

在PHP中,可以利用implode()函数的第一个参数来设置没有分隔符,该函数的第一个参数用于规定数组元素之间放置的内容,默认是空字符串,也可将第一个参数设置为空,语法为“implode(数组)”或者“implode("",数组)”。


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