Bubble Sort, bubblesort_PHP tutorial

Bubble Sort, bubblesort

8 numbers. Sort as ascend.

1st loop, compare 7 times (for 8 numbers), and found the largest 8.

2nd loop, compare 6 times (for 7 numbers), and found the largest 7.

. . .

1, 7, 8

2, 6, 7

3, 5, 6

4, 4, 5

5, 3, 4

6, 2, 3

7, 1, 2

In conclusion: For sorting 8 numbers, we need an outer loop of 7 times, each time for finding a largest number; and an inner loop from comparing 7 times to comparing 1 time (as in the center column).

Implementation in PHP:

<span> 1</span> <?<span>php
</span><span> 2</span> <span>/*</span><span> bubble sort: 
</span><span> 3</span> <span>    1. operate directly on the input array (&), not on a copy
</span><span> 4</span> <span>    2. sort as ascend
</span><span> 5</span> 
<span> 6</span> <span>    a is array
</span><span> 7</span> <span>    m is length of a
</span><span> 8</span> <span>    n is times of outer loop, n-i is times of comparing for each outer loop
</span><span> 9</span> <span>    i/j is for-loop counter
</span><span>10</span> <span>    w is for value swap
</span><span>11</span> <span>*/</span>
<span>12</span> <span>function</span> sortBubble(&<span>$a</span><span>){
</span><span>13</span>     <span>$m</span> = <span>count</span>(<span>$a</span><span>);
</span><span>14</span>     <span>$n</span> = <span>$m</span> - 1<span>;
</span><span>15</span>     <span>for</span>(<span>$i</span>=0; <span>$i</span><<span>$n</span>; <span>$i</span>++<span>){
</span><span>16</span>         <span>for</span>(<span>$j</span>=0; <span>$j</span><<span>$n</span>-<span>$i</span>; <span>$j</span>++<span>){
</span><span>17</span>             <span>if</span>(<span>$a</span>[<span>$j</span>] > <span>$a</span>[<span>$j</span>+1<span>]){
</span><span>18</span>                 <span>$w</span> = <span>$a</span>[<span>$j</span><span>];
</span><span>19</span>                 <span>$a</span>[<span>$j</span>] = <span>$a</span>[<span>$j</span>+1<span>];
</span><span>20</span>                 <span>$a</span>[<span>$j</span>+1] = <span>$w</span><span>;
</span><span>21</span> <span>            }
</span><span>22</span>             <span>else</span><span>{
</span><span>23</span>                 <span>//</span><span> do nothing</span>
<span>24</span> <span>            }
</span><span>25</span> <span>        }
</span><span>26</span>         <span>//</span><span> see the results after each outer loop
</span><span>27</span> <span>        // echo implode(', ', $a).'<br />';</span>
<span>28</span> <span>    }
</span><span>29</span> <span>}
</span><span>30</span> 
<span>31</span> <span>$arr</span> = <span>array</span>(9, 5, 2, 7, 3<span>);
</span><span>32</span> sortBubble(<span>$arr</span><span>);
</span><span>33</span> <span>echo</span> <span>implode</span>(', ', <span>$arr</span><span>);
</span><span>34</span> 
<span>35</span> <span>//</span><span> 2, 3, 5, 7, 9</span>
<span>37</span> ?>

Bubble sort c

Detailed notes on bubble sorting:
/* Use bubble sorting method to sort ten numbers in a one-dimensional integer array in ascending order*/
#include
#include

int main()
{
int i,j,t,a[10];
printf("Please input 10 integers:\n") ;
for(i=0;i<10;i++)
scanf("%d",&a[i]);
for(i=0;i<9;i++) /* Risk Bubble sorting*/
for(j=0;j<10-i-1;j++)
if(a[j]>a[j+1])
{t=a[ j];/* Swap a[i] and a[j] */
a[j]=a[j+1];
a[j+1]=t;
}
printf("The sequence after sort is:\n");
for(i=0;i<10;i++)
printf("%-5d",a[i]);
printf("\n");
system("pause");
return 0;
}
When i=0:
j starts from 0 a[0],a [1] Compare the sizes, give the larger one to a[1], then compare j++, a[1] and a[2], and then give the larger
of the two to a[2] , In this way, the largest of a[0], a[1], a[2] has been exchanged into a[2], and this process continues until j=10-i-1=9 like this
a[9 ] is the largest number among the 10 numbers.
Then when i=1:
Since the maximum number has been found and placed in a[9], this time the loop j only needs to reach a maximum of 10-i-1=8, that is, a[8]. , starting from j=0 again, a[j] and a[j+1] are compared and exchanged in pairs, and the last large number is placed in a[8]
Then i++, continue...
When i= At 9 o'clock, 9 pairwise comparisons have been made to complete all sorting, and i<9 is no longer true and the comparison is exited.
For n numbers, only n-1 pairwise comparisons in the outer loop are needed to complete the sorting.
As for sorting in descending order, just change if(a[j]>a[j+1]) to if(a[j]
-------------------------------------------------- -----------------------
/* Use the improved bubble sort method to sort the ten numbers in the one-dimensional integer array in ascending order*/
#include
#include
int main()
{int i,j,t,a[10],flag;
printf("Please input 10 integers:\n");
for(i=0;i<10;i++)
scanf("%d",&a[i]);
for(i =0;i<9;i++) /* Improved bubble sorting*/
{ flag=0;
for(j=0;j<10-i-1;j++)
if (a[j]>a[j+1])
{ t=a[j]; /* Swap a[i] and a[j] */
a[j]=a[j +1];
a[j+1]=t;
flag=1;
}
if(flag==0)break;
}
printf("The sequence after sort is:\n&...the rest of the text>>

Bubble sort c

Detailed notes on bubble sorting:
/* Use bubble sorting method to sort ten numbers in a one-dimensional integer array in ascending order*/
#include
#include

int main()
{
int i,j,t,a[10];
printf("Please input 10 integers:\n") ;
for(i=0;i<10;i++)
scanf("%d",&a[i]);
for(i=0;i<9;i++) /* Risk Bubble sorting*/
for(j=0;j<10-i-1;j++)
if(a[j]>a[j+1])
{t=a[ j];/* Swap a[i] and a[j] */
a[j]=a[j+1];
a[j+1]=t;
}
printf("The sequence after sort is:\n");
for(i=0;i<10;i++)
printf("%-5d",a[i]);
printf("\n");
system("pause");
return 0;
}
When i=0:
j starts from 0 a[0],a [1] Compare the sizes, give the larger one to a[1], then compare j++, a[1] and a[2], and then give the larger
of the two to a[2] ,In this way, the largest of a[0],a[1],a[2] has been exchanged into a[2], and this process continues until j=10-i-1=9 like this
a[9 ] is the largest number among the 10 numbers.
Then when i=1:
Since the maximum number has been found and placed in a[9], this time the loop j only needs to reach a maximum of 10-i-1=8, that is, a[8]. , starting from j=0 again, a[j] and a[j+1] are compared and exchanged in pairs, and the last large number is placed in a[8]
Then i++, continue...
When i= At 9 o'clock, 9 pairwise comparisons have been made to complete all sorting, and i<9 is no longer true and the comparison is exited.
For n numbers, only n-1 pairwise comparisons in the outer loop are needed to complete the sorting.
As for sorting in descending order, just change if(a[j]>a[j+1]) to if(a[j]
-------------------------------------------------- -----------------------
/* Use the improved bubble sort method to sort the ten numbers in the one-dimensional integer array in ascending order*/
#include
#include
int main()
{int i,j,t,a[10],flag;
printf("Please input 10 integers:\n");
for(i=0;i<10;i++)
scanf("%d",&a[i]);
for(i =0;i<9;i++) /* Improved bubble sorting*/
{ flag=0;
for(j=0;j<10-i-1;j++)
if (a[j]>a[j+1])
{ t=a[j]; /* Swap a[i] and a[j] */
a[j]=a[j +1];
a[j+1]=t;
flag=1;
}
if(flag==0)break;
}
printf("The sequence after sort is:\n&...the rest of the text>>

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