void quicksort(Student *students, int left, int right) { Student record = students[low]; while (low < high) { while (low<high &&students[high].score<=record.score) { --high; } students[low]=students[high]; while (low<high&&students[low].score>=record.score) { ++low; } students[high]=students[low]; } students[low]=record; quicksort(students,low,low-1); quicksort(students,low+1,high); }改进这段快速排序代码

这段快速排序代码有几个问题：

1. `low` 和 `high` 没有被定义，应该是 `left` 和 `right`；
2. 没有对边界情况进行处理，需要在递归出口处加上 `if (left >= right) return;`；
3. 在交换元素时，应该使用临时变量，而不是直接赋值。

改进后的代码如下：

void quicksort(Student *students, int left, int right) {
    if (left >= right) return;
    int low = left, high = right;
    Student record = students[low];
    while (low < high) {
        while (low < high && students[high].score <= record.score) {
            --high;
        }
        students[low] = students[high];
        while (low < high && students[low].score >= record.score) {
            ++low;
        }
        students[high] = students[low];
    }
    students[low] = record;
    quicksort(students, left, low - 1);
    quicksort(students, low + 1, right);
}

改进后的代码处理了边界情况，并使用临时变量进行了交换，可以更可靠地排序。