Searching and Sorting - A Concise and Practical Introduction to Programming Algorithms in Java - page 135

{
int tmp=array[i];
array[i]=array[j];
array[j]=tmp;
}

Sorting is an entire area field of computer science in itself with many algorithms
and remaining challenges to tackle. Next, we present two flagship algorithms:
The selection sort and quicksort.

6.4.1 Sorting by selection: SelectionSort

The selection sort is very natural and proceeds as follows:

- First, seek for the smallest element of the array: This is the SELECTION
stage.

- Then, reiterate the minimum selection for the remaining sub-array:

array[1], ..., array[n-1]

That is, at stage i+1, the selection sort seeks for the smallest elements for the
sub-array

array[j], array[j+1], ..., array[n-1]
To program the selection sort, we use two nested loops:

- The inner loop selects and puts the smallest element in front of the current
array,

- The outer loop repeats the minimum selection/swap for all subarrays.

These steps are summarized in the source code below:

Program 6.6 Sorting by selecting iteratively the minimum elements
static void swap ( int [ ] array , int i, int j)
{ int tmp=array [ i ]; array [ i]=array [ j ]; array [ j]=tmp; }

static void SelectionSort( int [] array)

int n=array . length ;

for ( int i=0;i < n − 1; i ++) {
for ( int j=i +1;j < n ; j ++) {
if (GreaterThan(array [ i ] , array [ j ]) )
swap(array , i , j ) ; }
}

}