快速排序（递归与非递归实现）

递归

public class QSort {
    /**
     * 找基准
     * @param array
     * @param low
     * @param high
     * @return
     */
    public static int partion(int[] array,int low,int high){
        int tmp = array[low];
        while(lowwhile(low < high && array[high] >= tmp){
                --high;
            }
            if(low >= high){
                break;
            }else{
                array[low] = array[high];
            }
            while(low < high && array[low] <= tmp){
                ++low;
            }
            if(low >= high){
                break;
            }else{
                array[high] = array[low];
            }
        }
        array[low] = tmp;
        return low;
    }
    public static void Quick(int[] array,int start,int end){
        int par = partion(array,start,end);
        if(par > start+1){
            Quick(array, start, par-1);
        }
        if(par < end-1){
            Quick(array, par+1, end);
        }
    }
    public static void QuickSort(int[] array){
        Quick(array,0,array.length-1);
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] array = {45,12,46,5,13,47,2};
        QuickSort(array);
        System.out.println(Arrays.toString(array));
    }

}

结果：

非递归

public class Qsort2 {
    /**
     * 找基准
     * @param array
     * @param low
     * @param high
     * @return
     */
    public static int partion(int[] array,int low,int high){
        int tmp = array[low];
        while(lowwhile(low < high && array[high] >= tmp){
                --high;
            }
            if(low >= high){
                break;
            }else{
                array[low] = array[high];
            }
            while(low < high && array[low] <= tmp){
                ++low;
            }
            if(low >= high){
                break;
            }else{
                array[high] = array[low];
            }
        }
        array[low] = tmp;
        return low;
    }
    public static void QuickSort(int[] array){
        int[] stack = new int[array.length];
        int top = 0;
        int low = 0;
        int high = array.length-1;
        int par = partion(array, low, high);
        //  入栈
        if(par > low+1){
            stack[top++] = low;
            stack[top++] = par-1;
        }
        if(par < high-1){
            stack[top++] = par+1;
            stack[top++] = high;
        }
        //出栈
        while(top > 0){
            high = stack[--top];
            low = stack[--top];
            par = partion(array, low, high);
            //再入栈
            if(par > low+1){
                stack[top++] = low;
                stack[top++] = par-1;
            }
            if(par < high-1){
                stack[top++] = par+1;
                stack[top++] = high;
            }
        }

    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] array = {5,8,4,3,6,7};
        QuickSort(array);
        System.out.println(Arrays.toString(array));
    }

}

结果：