单链表交换两结点

最新推荐文章于 2024-09-11 19:35:36 发布

亿次

最新推荐文章于 2024-09-11 19:35:36 发布

阅读量2.3k

点赞数 1

文章标签：链表数据结构 leetcode

本文链接：https://blog.youkuaiyun.com/m0_60352483/article/details/122161478

版权

该博客主要探讨了如何通过键盘随机输入非零整数建立单链表，然后实现根据给定索引交换链表中节点的功能。程序包括新建、交换、打印和释放链表的函数，确保了索引有效性和不同情况下的节点交换逻辑。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

题目描述：请填写缺失代码完成程序，实现如下功能：首先根据键盘随机输入，以0结束的若干非零整数建立单链表；然后根据输入的两个索引位置交换链表上的两个结点（链表首元素索引为1,

#include <stdio.h>

#include <malloc.h>

struct cell {//单链表结点结构体定义

    int x;

    struct cell* next;

};

struct cell* build(void) {//新建单链表，并将建好的单链表首结点地址返回

    struct cell* head, * tmp, * p;

    head = tmp = p = NULL;

    int n;



    head = (cell*)malloc(sizeof(cell));

    head->next = NULL;

    tmp = head;



    while (head != NULL) {

        scanf("%d", &n);

        if (n == 0)break;

        p = (cell*)malloc(sizeof(cell));

        p->x = n;

        tmp->next = p;

        p->next = NULL;

        tmp = p;

    }

    if (head->next == NULL) {

        free(head);

        head = NULL;

    }

    return head;//返回单链表头

}

struct cell* swap(struct cell* head, int m, int n) {//交换索引为m和n的两个结点，head是单链表首结点指针

    if (head == NULL) return NULL;

    struct cell* pm = head, * pn = head;

    struct cell* pm0 = NULL, * pn0 = NULL;

    struct cell* tmp;

    int i;



    for (i = 1; i < m && pm != NULL; i++) {

        pm0 = pm;

        pm = pm->next;

    }



    for (i = 1; i < n && pn != NULL; i++) {

        pn0 = pn;

        pn = pn->next;

    }



    if (pm != NULL && pn != NULL && m != n) {//索引为m,n的结点位于链表中间

        int temp;

        if (pm0 != NULL && pn0 != NULL) {//中间

            temp = pm->next->x; 

            pm->next->x = pn->next->x;

            pn->next->x = temp;

        }



        if (pm0 == NULL && pn0 != NULL) {  //pm0为头部 n>m

            temp = head->next->x;

            head->next->x = pn->next->x;

            pn->next->x = temp;

        }



        if (pm0 != NULL && pn0 == NULL) {  //pn0尾部  m>n

            temp = head->next->x;

            head->next->x = pm->next->x;

            pm->next->x = temp;

        }

    }

    return head;

}

void print(struct cell* head) {//打印整个单链表,head是单链表首结点指针

    struct cell* tmp, * p;

    tmp = head->next;

    while (tmp != NULL) {

        printf("%d", tmp->x);

        if (tmp->next != NULL)printf(" ");

        tmp = tmp->next;

    }

}

void release(struct cell* head) {//释放单链表空间,head是单链表首结点指针

    struct cell* temp, * p;

    temp = head;

    while (temp != NULL) {

        p = temp;

        temp = temp->next;

        free(p);

    }

}

int main(void) {

    struct cell* head;

    int m, n;

    head = build();

    scanf("%d %d", &m, &n);

    head = swap(head, m, n);

    if (head != NULL)

        print(head);

    else

        printf("NULL");

    release(head);

}