快排实现

递归实现

public Class QuickSort{
    public static void qSort(int[] array, int low, int high) {
        if (array == null) {
            return;
        }
        if (low < high) {
            int mid = patition(array, low, high);
            qSort(array, low, mid - 1);
            qSort(array, mid + 1, high);
        }
    }

    public static int patition(int[] array, int low, int high) {
        int start = low;
        int end = high;
        int temp = array[start];
        while (start < end) {
            while (start < end && array[end] >= temp)
                end--;
            array[start] = array[end];
            while (start < end && array[start] <= temp)
                start++;
            array[end] = array[start];
        }
        array[start] = temp;

        return start;
    }
}

非递归实现

public Class QuickSort{
    public static void qSort(int[] array, int start, int end){
        int low = start; 
        int high = end ;
        Stack<Integer> index = new Stack<Integer>();
        index.push(start);
        index.push(end);
        while(!index.isEmpty()){
            high = index.pop();
            low = index.pop();
            int position = partition(array, low, high);
            if(low < position - 1){
                index.push(low);
                index.push(position-1);
            }
            if(high > position + 1){
                index.push(position+1);
                index.push(high);           
            }       
        }
    }

    public static int partition(int[] array , int low, int high){
        int start = low;
        int end = high;
        int temp = array[low];
        while(start < end){
            while(start < end && array[end] > temp)
                end--;
            array[start] = array[end];
            while(start < end && array[start] < temp)
                start++;
            array[end] = array[start];
        }
        array[start] = temp;
        return start;
    }
}

常见排序一览表