计数排序

 

 

public class countSort {
    public static void main(String[] args) {
        int array[]= {-9,-8,-3,-11,8,6,5,2,7};
        System.out.println(Arrays.toString(countSort(array)));
    }
    public static int[] countSort(int array[]) {
        int min=array[0];
        int max=array[0];
        for (int i = 0; i < array.length; i++) {
            if (array[i]>max) {
                max=array[i];
            }
            if (array[i]<min) {
                min=array[i];
            }
        }
        //构建计数数组
        int count[]=new int[max-min+1];
        
        //构建处理后的排序数组
        int handleArray[]=new int[array.length];
        for (int i = 0; i < array.length; i++) {
            handleArray[i]=array[i]-min;
        }
        
        //计数到count数组中
        for (int i = 0; i < handleArray.length; i++) {
            count[handleArray[i]]++;
        }
        
        //构建处理后的count数组
        for (int i =1; i < count.length; i++) {
            count[i]+=count[i-1];
        }
        //
        for (int i=array.length-1;i>=0;i--) {
            array[count[handleArray[i]]-1]=handleArray[i]+min;
            count[handleArray[i]]--;
        }
        return array;
    }
}