A1052 Linked List Sorting (25 分)

链表排序算法解析
本文详细解析了如何使用静态存储方式对链表进行递增排序,通过定义节点结构体并利用map存储节点,实现了对链表的有效管理和排序,特别注意处理空链表情况。

1052 Linked List Sorting (25 分)

题目分析

       给我们一条链表,让我们根据结点值进行递增排序。链表采用的是静态存储的方式。

解题思路

       首先我们需要一个结构体node来存储结点,其中包括结点的关键字,地址,下一个结点的地址(所谓的地址就是一个五位的整数)。我们可以开一个100000大小的数组,把每个结点存储在地址对应的下标的位置,但是我更倾向于用map存储每个结点。这样可以应付地址位数更长的情况,避免数组开的太大。
       将所有结点储存完毕之后,我们从首地址startAddress开始对链表进行遍历,并将遍历到的结点储存在数组ans中,一直到startAddress等于-1为止,即链表结束。在这个过程中我们可以自动过滤掉不是本链表内的结点。然后就是根据关键字的值对每个结点进行排序。最后按照题意输出
       需要提醒注意的一点就是,题目中给出的链表可能为空!我一开始一直没有注意到这点,没有进行特判,导致有一个结点一直出现段错误。

AC代码

#include <cstdio>
#include <vector>
#include <algorithm>
#include <unordered_map>
using namespace std;

struct node{
	int key;
	int next, ad;
	node(){}
	node(int _key, int _next, int _ad): key(_key), next(_next), ad(_ad) {}
};

unordered_map<int, node> address;
vector<node> ans;
int n, startAddress, cnt = 0;
bool cmp(node a, node b) {
	return a.key < b.key;
}

int main() {
	scanf("%d%d", &n, &startAddress);
	int tempAddress, tempKey, tempNext;
	for (int i = 0; i < n; ++i) {
		scanf("%d %d %d", &tempAddress, &tempKey, &tempNext);
		address[tempAddress] = node(tempKey, tempNext, tempAddress);
	}
    while(startAddress != -1) {
    	ans.push_back(address[startAddress]);
    	cnt++;
    	startAddress = address[startAddress].next;
    }
    sort(ans.begin(), ans.end(), cmp);
    if (cnt == 0) // 这个特判很重要
        printf("0 -1\n");
    else {
       printf("%d %05d\n", cnt, ans[0].ad);
       for (int i = 0; i < ans.size(); ++i) {
        if (i != ans.size() - 1) {
            printf("%05d %d %05d\n", ans[i].ad, ans[i].key, ans[i + 1].ad);
        } else
            printf("%05d %d -1\n", ans[i].ad, ans[i].key);
       } 
    }
    return 0;
}


请参考我给出的代码框架,实现对EMPLOYEE结构体为数据的双向链表的排序算法,要求按照按employeeId升序排列 typedef struct linkNode { void* data; //使用空指针使得NODE适配多种数据结构 struct linkNode* preNode; struct linkNode* nextNode; }LINKED_NODE; /*Define the struct of double linked list.*/ typedef struct { LINKED_NODE* head; LINKED_NODE* tail; size_t size; }DOUBLE_LINK_LIST; typedef struct { int employeeId; char name[20]; char ipAddress[30]; char seatNumber[20]; char group[10]; } EMPLOYEE; DOUBLE_LINK_LIST* createDoubleLinkedList() { DOUBLE_LINK_LIST* newList = (DOUBLE_LINK_LIST*)malloc(sizeof(DOUBLE_LINK_LIST)); newList->head = NULL; newList->tail = NULL; newList->size = 0; return newList; } void destroyDoubleLinkedList(DOUBLE_LINK_LIST* list) {} /*Add a new node before the head.*/ void insertHead(DOUBLE_LINK_LIST* list, void* data) // void执政适配其他data类型? {} /*Add a new node after tail.*/ void insertTail(DOUBLE_LINK_LIST* list, void* data) // 如何适配其他data类型? {} /*Insert a new node.*/ void insertNode(DOUBLE_LINK_LIST* list, void* data,int index) // 如何适配其他data类型? {} void deleteHead(DOUBLE_LINK_LIST* list) {} void deleteTail(DOUBLE_LINK_LIST* list) {} void deleteNode(DOUBLE_LINK_LIST* list, int index) {} LINKED_NODE* getNode(DOUBLE_LINK_LIST* list, int index) {} /* 遍历链表,对每个节点执行指定操作*/ void traverseList(DOUBLE_LINK_LIST* list, void (*callback)(void*)) { LINKED_NODE* currentNode = list->head; while (currentNode != NULL) { callback(currentNode->data); currentNode = currentNode->nextNode; } } void printEmployee(void* data) {}
07-25
你可以使用以下代码来实现对EMPLOYEE结构体为数据的双向链表的排序算法,按照按employeeId升序排列: ```c #include <stdio.h> #include <stdlib.h> #include <string.h> typedef struct linkNode { void* data; //使用空指针使得NODE适配多种数据结构 struct linkNode* preNode; struct linkNode* nextNode; } LINKED_NODE; /*Define the struct of double linked list.*/ typedef struct { LINKED_NODE* head; LINKED_NODE* tail; size_t size; } DOUBLE_LINK_LIST; typedef struct { int employeeId; char name[20]; char ipAddress[30]; char seatNumber[20]; char group[10]; } EMPLOYEE; DOUBLE_LINK_LIST* createDoubleLinkedList() { DOUBLE_LINK_LIST* newList = (DOUBLE_LINK_LIST*)malloc(sizeof(DOUBLE_LINK_LIST)); newList->head = NULL; newList->tail = NULL; newList->size = 0; return newList; } void destroyDoubleLinkedList(DOUBLE_LINK_LIST* list) { LINKED_NODE* currentNode = list->head; while (currentNode != NULL) { LINKED_NODE* nextNode = currentNode->nextNode; free(currentNode); currentNode = nextNode; } free(list); } /*Add a new node before the head.*/ void insertHead(DOUBLE_LINK_LIST* list, void* data) { LINKED_NODE* newNode = (LINKED_NODE*)malloc(sizeof(LINKED_NODE)); newNode->data = data; newNode->preNode = NULL; newNode->nextNode = list->head; if (list->head != NULL) list->head->preNode = newNode; list->head = newNode; if (list->tail == NULL) list->tail = newNode; list->size++; } /*Add a new node after tail.*/ void insertTail(DOUBLE_LINK_LIST* list, void* data) { LINKED_NODE* newNode = (LINKED_NODE*)malloc(sizeof(LINKED_NODE)); newNode->data = data; newNode->preNode = list->tail; newNode->nextNode = NULL; if (list->tail != NULL) list->tail->nextNode = newNode; list->tail = newNode; if (list->head == NULL) list->head = newNode; list->size++; } /*Insert a new node.*/ void insertNode(DOUBLE_LINK_LIST* list, void* data, int index) { if (index < 0 || index > list->size) { printf("Invalid index\n"); return; } if (index == 0) { insertHead(list, data); return; } if (index == list->size) { insertTail(list, data); return; } LINKED_NODE* currentNode = getNode(list, index); LINKED_NODE* newNode = (LINKED_NODE*)malloc(sizeof(LINKED_NODE)); newNode->data = data; newNode->preNode = currentNode->preNode; newNode->nextNode = currentNode; currentNode->preNode->nextNode = newNode; currentNode->preNode = newNode; list->size++; } void deleteHead(DOUBLE_LINK_LIST* list) { if (list->head == NULL) return; LINKED_NODE* oldHead = list->head; list->head = oldHead->nextNode; if (list->head != NULL) list->head->preNode = NULL; free(oldHead); list->size--; if (list->size == 0) list->tail = NULL; } void deleteTail(DOUBLE_LINK_LIST* list) { if (list->tail == NULL) return; LINKED_NODE* oldTail = list->tail; list->tail = oldTail->preNode; if (list->tail != NULL) list->tail->nextNode = NULL; free(oldTail); list->size--; if (list->size == 0) list->head = NULL; } void deleteNode(DOUBLE_LINK_LIST* list, int index) { if (index < 0 || index >= list->size) { printf("Invalid index\n"); return; } if (index == 0) { deleteHead(list); return; } if (index == list->size - 1) { deleteTail(list); return; } LINKED_NODE* currentNode = getNode(list, index); currentNode->preNode->nextNode = currentNode->nextNode; currentNode->nextNode->preNode = currentNode->preNode; free(currentNode); list->size--; } LINKED_NODE* getNode(DOUBLE_LINK_LIST* list, int index) { if (index < 0 || index >= list->size) { printf("Invalid index\n"); return NULL; } LINKED_NODE* currentNode = list->head; int i = 0; while (i < index) { currentNode = currentNode->nextNode; i++; } return currentNode; } void traverseList(DOUBLE_LINK_LIST* list, void (*callback)(void*)) { LINKED_NODE* currentNode = list->head; while (currentNode != NULL) { callback(currentNode->data); currentNode = currentNode->nextNode; } } void printEmployee(void* data) { EMPLOYEE* employee = (EMPLOYEE*)data; printf("Employee ID: %d, Name: %s\n", employee->employeeId, employee->name); } int compareEmployee(const void* a, const void* b) { EMPLOYEE* employeeA = (EMPLOYEE*)a; EMPLOYEE* employeeB = (EMPLOYEE*)b; return employeeA->employeeId - employeeB->employeeId; } void sortList(DOUBLE_LINK_LIST* list) { size_t dataSize = sizeof(EMPLOYEE); EMPLOYEE** employeeArray = (EMPLOYEE**)malloc(list->size * sizeof(EMPLOYEE*)); LINKED_NODE* currentNode = list->head; size_t i = 0; while (currentNode != NULL) { employeeArray[i] = (EMPLOYEE*)currentNode->data; currentNode = currentNode->nextNode; i++; } qsort(employeeArray, list->size, dataSize, compareEmployee); currentNode = list->head; i = 0; while (currentNode != NULL) { currentNode->data = employeeArray[i]; currentNode = currentNode->nextNode; i++; } free(employeeArray); } int main() { DOUBLE_LINK_LIST* list = createDoubleLinkedList(); EMPLOYEE* employee1 = (EMPLOYEE*)malloc(sizeof(EMPLOYEE)); employee1->employeeId = 2; strcpy(employee1->name, "John"); insertHead(list, employee1); EMPLOYEE* employee2 = (EMPLOYEE*)malloc(sizeof(EMPLOYEE)); employee2->employeeId = 1; strcpy(employee2->name, "Alice"); insertHead(list, employee2); EMPLOYEE* employee3 = (EMPLOYEE*)malloc(sizeof(EMPLOYEE)); employee3->employeeId = 3; strcpy(employee3->name, "Bob"); insertHead(list, employee3); printf("Before sorting:\n"); traverseList(list, printEmployee); sortList(list); printf("\nAfter sorting:\n"); traverseList(list, printEmployee); destroyDoubleLinkedList(list); return 0; } ``` 这段代码首先定义了双向链表的结构体和EMPLOYEE结构体,然后实现了双向链表的创建、销毁、插入、删除、遍历等操作。其中,`sortList`函数使用了快速排序算法对双向链表中的EMPLOYEE结构体按照employeeId升序进行排序。在`main`函数中,创建了一个双向链表并插入了三个EMPLOYEE结构体,然后调用`sortList`函数对链表进行排序并输出结果。 请注意,在代码中使用了动态内存配(`malloc`)来配内存,并在适当的时候使用了`free`来释放内存,以防止内存泄漏。
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