PHP algorithm interview questions

1. use PHP to describe bubble sorting and quick sorting algorithms. The object can be an array. using PHP to describe sequential search and binary search (also called semi-query) algorithms, efficiency must be considered for sequential search. The object can be an ordered array 3. write a two-dimensional array sorting algorithm function... "> <LINKhref =" http://www.php100.com//statics/style/h

 

1. Use PHP to describe the bubble sort and quick sort algorithms. The object can be an array.

2. Using PHP to describe sequential search and binary search (also called semi-query) algorithms, sequential search must take efficiency into account. The object can be an ordered array.

3. Write a two-dimensional array sorting algorithm function that is universal and can call php built-in functions.

[Attached answer] (the answer below is not necessarily the best, but a simple reference)

I. Basic questions

1. Equal and unequal

2. true false

3. aaaaaa

4. 5 0 1

5. 5 2

6. 1 2

7. Get the extension of a file in more than five ways

Function get_ext1 ($ file_name ){

Return strrchr ($ file_name ,'.');

}

Function get_ext2 ($ file_name ){

Return substr ($ file_name, strrpos ($ file_name ,'.'));

}

Function get_ext3 ($ file_name ){

Return array_pop (explode ('.', $ file_name ));

}

Function get_ext4 ($ file_name ){

$ P = pathinfo ($ file_name );

Return $ p ['extension'];

}

Function get_ext5 ($ file_name ){

Return strrev (substr (strrev ($ file_name), 0, strpos (strrev ($ file_name ),'.')));

}

II. Algorithm questions

1. Use PHP to describe the bubble sort and quick sort algorithms. The object can be an array.

// Bubble sort (array sorting)

Function bubble_sort ($ array)

{

$ Count = count ($ array );

If ($ count <= 0) return false;

For ($ I = 0; $ I <$ count; $ 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;

}

// Fast sorting (array sorting)

Function quick_sort ($ array ){

If (count ($ array) <= 1) return $ array;

$ Key = $ array [0];

$ Left_arr = array ();

$ Right_arr = array ();

For ($ I = 1; $ I

If ($ array [$ I] <= $ key)

$ Left_arr [] = $ array [$ I];

Else

$ Right_arr [] = $ array [$ I];

}

$ Left_arr = quick_sort ($ left_arr );

$ Right_arr = quick_sort ($ right_arr );

Return array_merge ($ left_arr, array ($ key), $ right_arr );

}

2. Using PHP to describe sequential search and binary search (also called semi-query) algorithms, sequential search must take efficiency into account. The object can be an ordered array.

// Binary search (find an element in the array)

Function bin_sch ($ array, $ low, $ high, $ k ){

If ($ low <= $ high ){

$ Mid = intval ($ low + $ high)/2 );

If ($ array [$ mid] === k ){

Return $ mid;

} Elseif ($ k <$ array [$ mid]) {

Return bin_sch ($ array, $ low, $ mid-1, $ k );

} Else {

Return bin_sch ($ array, $ mid + 1, $ high, $ k );

}

}

Return-1;

}

// Sequential search (find an element in the array)

Function seq_sch ($ array, $ n, $ k ){

$ Array [$ n] = $ k;

For ($ I = 0; $ I <$ n; $ I ++ ){

If ($ array [$ I] === k ){

Break;

}

}

If ($ I <$ n ){

Return $ I;

} Else {

Return-1;

}

}

3. Write a two-dimensional array sorting algorithm function that is universal and can call php built-in functions.

// Two-dimensional array sorting. $ arr indicates data, $ keys indicates the key value of sorting, $ order indicates sorting rules, 1 indicates ascending, and 0 indicates descending.

Function array_sort ($ arr, $ keys, $ order = 0 ){

If (! Is_array ($ arr )){

Return false;

}

$ Keysvalue = array ();

Foreach ($ arr as $ key => $ val ){

$ Keysvalue [$ key] = $ val [$ keys];

}

If ($ order = 0 ){

Asort ($ keysvalue );

} Else {

Arsort ($ keysvalue );

}

Reset ($ keysvalue );

Foreach ($ keysvalue as $ key => $ vals ){

$ Keysort [$ key] = $ key;

}

$ New_array = array ();

Foreach ($ keysort as $ key => $ val ){

$ New_array [$ key] = $ arr [$ val];

}

Return $ new_array;

}