快速排序有点问题

[NewshiJ]

我写了一个快速排序，但是排序结果是局部有序的不知道代码哪里有问题，请各位大牛来看看

package data_structure.sort;

public class Fast_2 {
	public static  void sort(int[] a) {
		sort(a, 0, a.length-1);
	}
	
	private static  void sort(int[]a,int low,int high) {
		int key = a[low];
		int k = low;
		boolean go = false;
		int l = low;
		int h = high;
		while(l<h){
			while(go){
				if(a[l]>key){        //正向
					a[k] = a[l];
					a[l] = key;
					go = false;
					k = l;
				}
				l++;
			}
			while(!go){
				if(a[h]<=key){			//反向
					a[k] = a[h];
					a[h] = key;
					go = true;
					k = h;
				}
				h--;
			}
		}
		if((high-low)<2)
			return;
		sort(a, low, k);
		sort(a, k+1, high);
	}
	
	public static void main(String[] args) {
		int a [] =new int[]{5,3,31,9,8,15,35,7,6,8,9,4,8,10,0};
		sort(a);
		for (int i : a) {
			System.out.print(i+" ");
		}
	}
}

[soton_dolphin]

你的快速排序少了partition这个方法啊 algorithm quicksort(A, lo, hi) is if lo < hi then p := partition(A, lo, hi) quicksort(A, lo, p) quicksort(A, p + 1, hi) algorithm partition(A, lo, hi) is pivot := A[lo] i := lo - 1 j := hi + 1 loop forever do: i := i + 1 while A[i] < pivot do do: j := j - 1 while A[j] > pivot do if i >= j then return j swap A[i] with A[j]

[晴天_ccc]

private static void sort(int[] a, int low, int high) {
        int key = a[low];
        int k = low;
        int l = low;
        int h = high;
        while (l < h) {
            while (l < h && a[h] >= key) {
                h--;
            }

            a[k] = a[h];
            System.out.println("[" + a[h] + "][" + h + "->" + k + "]");
            k = h;

            while (l < h && a[l] <= key) {
                l++;
            }
            a[k] = a[l];
            System.out.println("[" + a[l] + "][" + l + "->" + k + "]");
            k = l;

        }
        a[l] = key;

        if (high - low > 1) {
            sort(a, low, k);
            if (k + 1 < high)
                sort(a, k + 1, high);
        }
    }

    public static void main(String[] args) {
        int a[] = new int[] { 5, 3, 31, 9, 8, 15, 35, 7, 6, 8, 9, 4, 8, 10, 0 };
        for (int i : a) {
            System.out.print(i + " ");
        }
        System.out.println();
        sort(a, 0, a.length - 1);
        for (int i : a) {
            System.out.print(i + " ");
        }
    }

[NewshiJ]

引用 1 楼 soton_dolphin 的回复:

你的快速排序少了partition这个方法啊 algorithm quicksort(A, lo, hi) is if lo < hi then p := partition(A, lo, hi) quicksort(A, lo, p) quicksort(A, p + 1, hi) algorithm partition(A, lo, hi) is pivot := A[lo] i := lo - 1 j := hi + 1 loop forever do: i := i + 1 while A[i] < pivot do do: j := j - 1 while A[j] > pivot do if i >= j then return j swap A[i] with A[j]

我不是很明白，我在方法内部递归调用本放法了

[NewshiJ]

引用 2 楼 q583900890 的回复:

private static void sort(int[] a, int low, int high) {
        int key = a[low];
        int k = low;
        int l = low;
        int h = high;
        while (l < h) {
            while (l < h && a[h] >= key) {
                h--;
            }

            a[k] = a[h];
            System.out.println("[" + a[h] + "][" + h + "->" + k + "]");
            k = h;

            while (l < h && a[l] <= key) {
                l++;
            }
            a[k] = a[l];
            System.out.println("[" + a[l] + "][" + l + "->" + k + "]");
            k = l;

        }
        a[l] = key;

        if (high - low > 1) {
            sort(a, low, k);
            if (k + 1 < high)
                sort(a, k + 1, high);
        }
    }

    public static void main(String[] args) {
        int a[] = new int[] { 5, 3, 31, 9, 8, 15, 35, 7, 6, 8, 9, 4, 8, 10, 0 };
        for (int i : a) {
            System.out.print(i + " ");
        }
        System.out.println();
        sort(a, 0, a.length - 1);
        for (int i : a) {
            System.out.print(i + " ");
        }
    }

package data_structure.sort;

public class Fast_2 {
	public static  void sort(int[] a) {
		sort(a, 0, a.length-1,new a());
	}
	static class a{
		int n =1;
	}
	private static  void sort(int[]a,int low,int high,a n) {
		System.out.println("第"+n.n+"次排序前");
		n.n++;
		for (int i : a) {
			System.out.print(i+" ");
		}		
		int key = a[low];
		int k = low;
		boolean go = false;
		int l = low;
		int h = high;
		System.out.println();
		System.out.println("-----起始点: a["+low+"]="+key+" -----结束点: a["+high+"]="+a[high]+"-----比较值:"+key+"---步长:"+(high-low));
		while(l<=h){
			while(go&&l<=h){
				if(a[l]>key){        //正向
					a[k] = a[l];
					a[l] = key;
					go = false;
					k = l;
				}
				l++;
			}
			while(!go&&l<=h){
				if(a[h]<=key){			//反向
					a[k] = a[h];
					a[h] = key;
					go = true;
					k = h;
				}
				h--;
			}
		}		
		for (int i : a) {
			System.out.print(i+" ");
		}
		System.out.println();
		System.out.println();
		if((high-low)<2)
			return;
		if(a[low]==a[high])
			return;
		if(k>low)			
			sort(a, low, k,n);
		if(high>k+1)
			sort(a, k+1, high,n);
	}
	
	
	public static void main(String[] args) {
		int a [] =new int[]{7,5,3,31,9,8,15,35,7,6,8,9,4,10,0,20,17,1,18,8,8};
		System.out.println("开始排序!");
		for (int i : a) {
			System.out.print(i+" ");
		}
		System.out.println();
		System.out.println();
		
		sort(a);
		for (int i : a) {
			System.out.print(i+" ");
		}
	}
}

谢谢你的帮助我找到原因了，我把你的代码进行了一下优化判断，同样一份数据排序次数降低了几次，当一趟排序后末位数与第一位数相同，则不进入下一次排序，就减少了相同数据的排序次数