Select Sort

character:the range of sorted array extends as the index steps forward.when the sort process is down,the given array is sorted.

firstly we need some subsidiray functions:

private int findMinIndex(Comparable[]a,int start,int end){
    int len=a.length;
    assert 0==len;
    boolean rightFormat= (start<=end);
    boolean startInclude=(start >=0 ) && (start<len);
    boolean endInclude=(end >=0 ) && (end<len);
    assert (!rightFormat) || (!startInclude) || (!endInclude);

    int minIndex=start;
    Comparable min=a[start];
    for(int i=start+1;i<=end;++i){
        if(InsertSort.less(a[i],min)){
            min=a[i];
            minIndex=i;
        }
    }
    return minIndex;
}
as to the swap() and less() function ,refer to the introduction in InsertSort.

then we can code the sort function as below:

public void selectSort(Comparable[] a){
    int len=a.length;
    assert len==0;
    if(1==len) return;

    for(int i=0;i<len-1;++i){
        int minIndex=findMinIndex(a,i+1,len-1);
        if(less(a[minIndex],a[i])) {
            swap(a, minIndex, i);
        }
    }
}

the code explains itself.doesn't it?