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用C++编程 ,快速排序非递归算法

用C++编程 ,快速排序非递归算法

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知与谁同 2018-07-22 14:34:00 1982 0
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  • #include <iostream>
    using namespace std;

    int partition(int *a, int l, int h)
    {
    int x = a[l];
    int i = l;
    int j = h+1;
    int temp;

    while (i<j)
    {
    while (a[++i]<x&&i<h);
    while(a[--j]>x);

    if (i<j)
    {
    temp = a[i];
    a[i] = a[j];
    a[j] = temp;
    }
    }

    a[l] = a[j];
    a[j] = x;

    return j;
    }

    void qsort(int *a, int l, int h)
    {
    if (l>=h)
    return;

    int *s = new int[h-l+1];
    int p = 0;
    s[p++] = l;
    s[p++] = h;

    int low,high,q;

    while (p>0)
    {
    high = s[--p];
    low = s[--p];
    if (low>=high)
    break;

    q = partition(a, low, high);

    if (q-low > high-q)
    {
    s[p++] = low;
    s[p++] = q-1;

    if (high > q)
    {
    s[p++] = q+1;
    s[p++] = high;
    }

    }
    else
    {
    s[p++] = q+1;
    s[p++] = high;
    if (q > low)
    {
    s[p++] = low;
    s[p++] = q-1;
    }
    }
    }
    delete []s;
    }

    int main()
    {
    int a[9] = {9,8,7,6,5,4,3,2,1};
    //int a[9] = {1,2,3,4,5,6,7,8,9};
    qsort(a,0,8);

    for (int i=0; i<9; i++)
    cout<<a[i]<<endl;

    return 0;
    }
    2019-07-17 22:55:02
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