快速排序

void quicksort(int left, int right){    int i, j, x;    i = left;    j = right;    if(i >= j) return;    x = a[i];    while(i < j)    {        while(i < j && a[j] > x) j--;        if(i < j) a[i++] = a[j];              while(i < j && a[i] < x) i++;        if(i < j) a[j--] = a[i];    }    a[i] = x;    if(left < i - 1) quicksort(left, i - 1);    if(i + 1 < right) quicksort(i + 1, right);}