C语言实现链表基本操作（交换第i个和第j个节点）

当i或者j为1时，需要让链表的表头指向j。

代码为

/*i和j为1时情况比较特殊，需要让表头重新指向交换后的那个节点*/
if (i == 1) {
t1 = *L;
for (m = 1; temp->Next != NULL; m++, temp = temp->Next) {
if (m + 1 == j) {
*L = temp->Next;
t2 = temp->Next->Next;
temp->Next->Next = t1->Next;
t1->Next = t2;
temp->Next = t1;
}
}
}

当i和j都不为1时。
节点相邻与不相邻也是不一样的。
不相邻的情况下就是让i前面的节点指向j，然后让j前面的节点指向i。如果两个节点相邻（假设i < j）j前面的节点就是i，j前面的节点指向i就是指向了自己，所以要分开写。
不相邻节点时：




代码为：

if ((i - j) != 1 && (j- i) != 1) {//非相邻结点之间交换
for (m = 1; temp->Next != NULL; m++, temp = temp->Next) {
if (m + 1 == i) {
t1 = temp;
}
if (m + 1 == j) {
t2 = temp;
}
}
t5 = t1->Next->Next;
t3 = t1->Next;
t4 = t2->Next;
t1->Next = t4;
t2->Next = t3;
t3->Next = t4->Next;
t4->Next = t5;
}

最后一种情况，两个节点相邻：




代码为：

for (m = 1; temp != NULL; m++, temp = temp->Next) {
if (m + 1 == i) {
t1 = temp;
}
if (m == j) {
t2 = temp;
}
}
temp = t2->Next;
t3 = t1->Next;
t1->Next = t2;
t3->Next = temp;
t2->Next = t3;
}

全部代码：

#include <stdio.h>
#include <malloc.h>

typedef struct node
{
int Score;
struct node * Next;
}Node, * List;

void Insert(List *L, Node e)
{
List temp = *L;
List n = (List)malloc(sizeof(Node));
n->Score = e.Score;
if (temp == NULL) {
*L = n;
}
else {
while (temp->Next != NULL) {
temp = temp->Next;
}
temp->Next = n;
}
n->Next = NULL;
}

void Swap(List * L, int i, int j)
{
List temp = *L;
List t1;
List t2;
List t3;
List t4;
List t5;
int m;
/*i和j为1时情况比较特殊，需要让表头重新指向交换后的那个节点*/
if (i == 1) {
t1 = *L;
for (m = 1; temp->Next != NULL; m++, temp = temp->Next) {
if (m + 1 == j) {
*L = temp->Next;
t2 = temp->Next->Next;
temp->Next->Next = t1->Next;
t1->Next = t2;
temp->Next = t1;
}
}
}if (j == 1) {
t1 = *L;
for (m = 1; temp->Next != NULL; m++, temp = temp->Next) {
if (m + 1 == i) {
*L = temp->Next;
t2 = temp->Next->Next;
temp->Next->Next = t1->Next;
t1->Next = t2;
temp->Next = t1;
}
}
}
/*相邻节点之间交换和非相邻结点之间交换不一样*/
else {
if ((i - j) != 1 && (j- i) != 1) {//非相邻结点之间交换
for (m = 1; temp->Next != NULL; m++, temp = temp->Next) {
if (m + 1 == i) {
t1 = temp;
}
if (m + 1 == j) {
t2 = temp;
}
}
t5 = t1->Next->Next;
t3 = t1->Next;
t4 = t2->Next;
t1->Next = t4;
t2->Next = t3;
t3->Next = t4->Next;
t4->Next = t5;
}else if (i < j) {//相邻节点之间交换
for (m = 1; temp != NULL; m++, temp = temp->Next) {
if (m + 1 == i) {
t1 = temp;
}
if (m == j) {
t2 = temp;
}
}
temp = t2->Next;
t3 = t1->Next;
t1->Next = t2;
t3->Next = temp;
t2->Next = t3;
}else if (i > j) {
for (m = 1; temp != NULL; m++, temp = temp->Next) {
if (m + 1 == j) {
t1 = temp;
}
if (m == i) {
t2 = temp;
}
}
temp = t2->Next;
t3 = t1->Next;
t1->Next = t2;
t3->Next = temp;
t2->Next = t3;
}
}
}

void printflist(List list)
{
List temp;
for (temp = list; temp != NULL; temp = temp->Next) {
printf("%d\n", temp->Score);
}
}

void freelist(List *list)
{
List temp = *list, del;
while (temp != NULL) {
del = temp;
temp = temp->Next;
free(del);
}
}

int main()
{
List list = NULL;
Node n1, n2, n3, n4, e;//定义5个节点
e.Score = 5;
n1.Score = 1;
n2.Score = 2;
n3.Score = 3;
n4.Score = 4;
Insert(&list, n1);
Insert(&list, n2);
Insert(&list, n3);
Insert(&list, n4);
Insert(&list, e);
// dellist(&list, 8);
Swap(&list, 5, 4);
printflist(list);
freelist(&list);
return 0;
}