STU* selectionSort(STU* head) { if (head == NULL || head->next == NULL) { return head; } STU* dummyHead = (STU*)malloc(sizeof(STU)); if (dummyHead == NULL) { printf("内存分配失败!\n"); return NULL; } dummyHead->next = head; STU* current = dummyHead->next; STU* min = NULL; STU* temp = NULL; while (current != NULL) { min = current; temp = current->next; while (temp != NULL) { int sum_current = current->score[0] + current->score[1] + current->score[2]; int sum_temp = temp->score[0] + temp->score[1] + temp->score[2]; double avg_current = (double)sum_current / 3; double avg_temp = (double)sum_temp / 3; if (avg_temp < avg_current) { min = temp; } temp = temp->next; } OutOneNode(current); if (min != current) { // 交换节点的数据 int temp_score[3]; memcpy(temp_score, current->score, sizeof(current->score)); memcpy(current->score, min->score, sizeof(min->score)); memcpy(min->score, temp_score, sizeof(temp_score)); } current = current->next; } STU* sortedHead = dummyHead->next; free(dummyHead); return sortedHead; }选择法排序,这个代码有什么问题?
时间: 2024-04-07 20:33:27 浏览: 13
这段代码实现了一个选择排序的算法,但是存在一些问题。
1. 在函数开头,对头指针进行了判空操作,但没有对头指针的数据域进行判空操作。如果数据域为空,可能会导致后续的求和和平均值计算出错。
2. 在定义 dummyHead 结点时,使用了动态内存分配函数 malloc,但没有对内存分配结果进行判空操作。如果分配内存失败,会导致后续的代码出现问题。
3. 在选择最小值的内层循环中,没有更新 min 结点的指针。在找到更小的结点时,应该更新 min 指向该结点。
4. 在交换节点数据的代码中,使用了 memcpy 函数进行数组数据的交换,但是没有考虑到数组长度的问题。应该将 sizeof(current->score) 替换为 sizeof(current->score[0]) * 3。
综上所述,可以对代码进行以下改进:
```
STU* selectionSort(STU* head) {
if (head == NULL || head->next == NULL) {
return head;
}
STU* dummyHead = (STU*)malloc(sizeof(STU));
if (dummyHead == NULL) {
printf("内存分配失败!\n");
return NULL;
}
dummyHead->next = head;
STU* current = dummyHead->next;
STU* min = NULL;
STU* temp = NULL;
while (current != NULL) {
min = current;
temp = current->next;
while (temp != NULL) {
int sum_current = current->score[0] + current->score[1] + current->score[2];
int sum_temp = temp->score[0] + temp->score[1] + temp->score[2];
double avg_current = (double)sum_current / 3;
double avg_temp = (double)sum_temp / 3;
if (avg_temp < avg_current) {
min = temp;
}
temp = temp->next;
}
OutOneNode(current);
if (min != current) {
int temp_score[3];
memcpy(temp_score, current->score, sizeof(current->score[0]) * 3);
memcpy(current->score, min->score, sizeof(min->score[0]) * 3);
memcpy(min->score, temp_score, sizeof(temp_score));
}
current = current->next;
}
STU* sortedHead = dummyHead->next;
free(dummyHead);
return sortedHead;
}
```
这样修改后,代码应该能够正常运行了。