Introduction to bubbling, binary insertion, and quick sort algorithms

1. Bubble sorting algorithm
Process:
1. Traverse the entire array and compare every pair of adjacent elements, such as $ a[$i]>$a[$i 1] swaps positions, and each comparison eliminates a reverse order.
2. After each cycle, the number of times it needs to be cycled next time is reduced by 1.

'; } function popsort(&$arr){ for($i=0,$length=count($arr)-1; $i<$length; $i++){ for($j=0; $j<$length-$i; $j++){ if($arr[$j]>$arr[$j+1]){ $tmp = $arr[$j]; $arr[$j] = $arr[$j+1]; $arr[$j+1] = $tmp; } } } } ?>

2. Dichotomous insertion sort

Process:
1. First of all, the original array is an ordered sequence, $low=0 $high=count($arr)-1.
2. Compare the number to be inserted with the element in the middle of the array.
If it is larger than the middle element, $low=$mid 1 will be used as the beginning of the array for the next judgment.
If it is smaller than the middle element, $high=$mid-1 will be used as the end of the array for the next judgment.
3. Until $low>$high ends, $low is the position where the new element is inserted.
4. Move all elements starting from $low in the array backward by one, and then insert new elements at the $low position.

'; binsort($arr, $key); printarr($arr); function createarr($num=10){ $arr = array(); for($i=0; $i<$num; $i++){ array_push($arr, mt_rand(0,99)); } sort($arr); // 有序序列 return $arr; } function printarr($arr){ echo 'arr:'.implode(',', $arr).'
'; } function binsort(&$arr, $key){ $low = 0; $high = count($arr)-1; while($low<=$high){ $m = $low + (int)(($high-$low)/2); $mkey = $arr[$m]; if($key>=$mkey){ $low = $m + 1; }else{ $high = $m - 1; } } // 移动插入位置之后的元素,插入新元素 for($i=count($arr)-1; $i>=$low; $i--){ $arr[$i+1] = $arr[$i]; } $arr[$low] = $key; } ?>

3. Quick sort
Process:
1. Find an element in the array as the key, usually The first element of the array is used as the key
2. i=0, j=array length-1
3. j-- When arr[j] 4. i When arr[i]>key, arr[i] and arr[j] exchange positions
5. Repeat 3,4 until i==j, complete.
6. Execute 1, 2, 3, 4, 5 (recursively) for the left and right sets of elements separated by key.

'; } function quicksort(&$arr, $low, $high){ if($low>=$high){ return ; } $key = $arr[$low]; $i = $low; $j = $high; $flag = 1; while($i!=$j){ switch($flag){ case 0: if($arr[$i]>$key){ $tmp = $arr[$i]; $arr[$i] = $arr[$j]; $arr[$j] = $tmp; $flag = 1; }else{ $i++; } break; case 1: if($arr[$j]<$key){ $tmp = $arr[$i]; $arr[$i] = $arr[$j]; $arr[$j] = $tmp; $flag = 0; }else{ $j--; } break; } } quicksort($arr, $low, $i-1); quicksort($arr, $i+1, $high); } ?>

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