选择排序

最简单的一种排序：选择排序

public class SelectionSort {

    private void swap(int i,int j,int[] arr){
        int tem = arr[j];
        arr[j] = arr[i];
        arr[i] = tem;
    }

    public void selectionSort(int[] arr){

        if(arr == null||arr.length < 2 ){
            return;
        }

        int length = arr.length;

        for(int i = 0;i < length - 1;i++){
            int minIndex = i;
            for(int j = i+1;j < length;j++){
                //每一轮中找出最小值的下标
                minIndex = arr[j] < arr[minIndex] ? j : minIndex;
            }
            swap(minIndex,i,arr);
        }

    }

	//test
    public static void main(String[] args){

        int[] arr = {2,7,1,1,2,2,3,3,1,1,9,7};
        SelectionSort sort = new SelectionSort();
        sort.selectionSort(arr);

        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }

    }

}