二路归并，有一步无法理解，希望有明白的指点一下! - C语言论坛

已结贴√ 问题点数：16 回复次数：3

二路归并，有一步无法理解，希望有明白的指点一下!

单链表的二路归并算法：
    已经产生两单链表，要将这两个单链表再不分配新的情况下并入一个新的单链表中，让一个已存在的链表的头结点作为新链表的头结点，在创建一个指针一直指向新链表的尾结点；
    void erlu(SLinkNode *ha,SLinkNode *hb,SLinkNode *hc)
    {
        SLinkNode *pa=ha->next;*pb=hb->next;*tc;
        hc=ha;       //将ha的头节点作为hc的头结点

        tc=hc;       //让tc一直指向hc的尾节点

        free(hb);
这是我从书上抄的一段代码，hc是要二路并入后的链表
      我想问一下这个里面   tc=hc;  让tc指向hc尾节点，为什么可以这样写，感觉怪怪的，不知道怎么理解，希望有理解的给我解释一下，我对于链表的理解是不是有什么遗漏！

搜索更多相关主题的帖子: 单链表　链表　 tc　二路归并　结点　

第 2 楼

得分:8

after the statement tc = hc, insert printf to check out the address of the list pointer(tc)
tc = hc;
printf("tc = %p, hc = %p\n", tc, hc);

good luck!

第 3 楼

得分:0

another reference:
https://blog.

第 4 楼

得分:0

//online parser: https://www.bccn.net/run/

程序代码：

#include <stdio.h>
#include <stdlib.h>

#pragma GCC diagnostic ignored "-Wint-conversion"

typedef int ElmeType;

typedef struct node{
    ElmeType data;
    struct node *next;
}SLinkNode, *PSN;

//#define PRINT_ON

//For keeping prototype disusing **L
void InitList(SLinkNode *L)
{
    PSN M;

//#define SET_ADDR(_m) *(int *)(_m)
    //SET_ADDR(L) = (PSN)malloc(sizeof(SLinkNode));
#ifdef PRINT_ON
    //printf("*L = %p\n", L);
#endif
    M = (PSN)malloc(sizeof(SLinkNode));
#define CAST2IDA(_m, _ida) ((PSN)(&(*_m)))->_ida
    CAST2IDA(L, data) = M;
    M->data = 125;
    M->next = NULL;
#ifdef PRINT_ON
    printf("M(*L) = %p\n", M);
    printf("M->data = %d\n", M->data);
    printf("M->next = %p\n", M->next);
    printf("end of %s\n", __func__);
#endif
}

int main(int argc, char *argv[])
{
    SLinkNode *L = (PSN)InitList;

    InitList((PSN)&L);

#ifdef PRINT_ON
    printf("L = %p\n", L);
    printf("L->data = %d\n", L->data);
    printf("L->next = %p\n", L->next);
    printf("end of %s\n", __func__);
#endif
    free(L);

    return 0;
}

output sample:

M(*L) = 0x672010
M->data = 125
M->next = (nil)
end of InitList
L = 0x672010
L->data = 125
L->next = (nil)
end of main

[此贴子已经被作者于2021-9-26 14:53编辑过]

第 5 楼

得分:0

//online parser: https://www.bccn.net/run/

程序代码：

#include <stdio.h>
#include <stdlib.h>

#pragma GCC diagnostic ignored "-Wint-conversion"

//#define PRINT_ON
#define STATE_POLL 0
#define Trans_real_Arg 0

typedef int ElmeType;
typedef struct node {
    ElmeType data;
    struct node *next;
}SLinkNode, *PSN;

#define stub
#define public typedef
#define class struct
//portable oo-style ??
public class  v {
    unsigned char state;
    PSN addr;
    int vtbl[2];
}vs, *pvs;

static pvs vm;

//bottom layer
void __post_local_address(PSN addr)
{
    vm->addr = addr;
#ifdef PRINT_ON
    printf("addr = %p\n", addr);
    printf("vm->addr = %p\n", vm->addr);
#endif
}

PSN __recv_external_address(void)
{
    return vm->addr;
}

//mid layer
void _register_state_func(int fa)
{
    static int idx = 0;
    
    vm->vtbl[idx++] = fa;
    //boundary alert: state < 0xFF
    vm->state++;
}

int _main(int argc, char **argv)
{
    //BUG_ON
    vm = (pvs)malloc(sizeof(vs));
    //interface register mannually
    _register_state_func(__post_local_address);
    _register_state_func(__recv_external_address);
    
#ifdef PRINT_ON
    printf("vm = %p\n", vm);
    printf("end of %s\n", __func__);
#endif

    return 0;
}

//For keeping prototype disusing **L
void InitList(SLinkNode *L)
{
    PSN M;
    
    M = (PSN)malloc(sizeof(SLinkNode));

#if Trans_real_Arg == 0
typedef int (*ra)(void);
#define RDY_STATE(_s) (_s >> 4) & 0x01
    //Address trunc occurred!!!
    //L = ((ra)(vm->vtbl[STATE_POLL + RDY_STATE(vm->state)]))();
    //no trunc!
    L = __recv_external_address();
#ifdef PRINT_ON
    printf("revc L = %p\n", L);
#endif
#endif//Trans_real_Arg block

//#define SET_ADDR(_m) *(int *)(_m)
    //SET_ADDR(L) = (PSN)malloc(sizeof(SLinkNode));
#define CAST2IDA(_m, _ida) ((PSN)(&(*_m)))->_ida
    CAST2IDA(L, data) = M;
    M->data = 125;
    M->next = NULL;
#ifdef PRINT_ON
    printf("M(*L) = %p\n", M);
    printf("M->data = %d\n", M->data);
    printf("M->next = %p\n", M->next);
    printf("end of %s\n", __func__);
#endif
}

//main branch top layer
int main(int argc, char *argv[])
{
    int i = 1;

    SLinkNode *L = (PSN)InitList;
#ifdef PRINT_ON
    printf("L(addr) = %p\n", &L);
#endif
#define  T_PTR(_p) (void *)(_p)
    _main(1, T_PTR("register callback function"));
#if Trans_real_Arg == 1
    //Transfering real arguments
    InitList((PSN)&L);
#else//Trans_real_Arg block
#define LOWBYTE(_b) (_b) & 0x0f
#define STATE_N(_s) LOWBYTE(_s)
    while (i++ < STATE_N(vm->state)) {
#define RDY_POST(_s) ((_s) >> 4) & 0x01
        if (!RDY_POST(vm->state)) {
typedef void (*pa)(int);
#ifdef PRINT_ON
            //BUG_ON trunc address
            printf("__int64 trunc: &L = %p\n", (PSN)&L);
#endif
            //Address trunc occurred!!!
            //((pa)(vm->vtbl[STATE_POLL + 0]))((PSN)&L);
            //no trunc!
            __post_local_address((PSN)&L);
#define SET_POST(_s) (_s) |= 0x10
            SET_POST(vm->state);
            //Transfering formal arguments ? 2333
            InitList(L);
        } else {
#define bus_stub
            bus_stub;
#define switch_ctx()
            switch_ctx();
        }
    }
#endif//Trans_real_Arg

#ifdef PRINT_ON
    printf("L = %p\n", L);
    printf("L->data = %d\n", L->data);
    printf("L->next = %p\n", L->next);
    printf("end of %s\n", __func__);
#endif
    free(L);

    return 0;
}

output sample:

L(addr) = 0x7ffd15da8860
vm = 0x1dde020
end of _main
__int64 trunc: &L = 0x7ffd15da8860
addr = 0x7ffd15da8860
vm->addr = 0x7ffd15da8860
revc L = 0x7ffd15da8860
M(*L) = 0x1dde040
M->data = 125
M->next = (nil)
end of InitList
L = 0x1dde040
L->data = 125
L->next = (nil)
end of main

第 6 楼

得分:8

你滴代码没抄全

void erlu(SLinkNode *ha,SLinkNode *hb,SLinkNode *hc)
    {
        SLinkNode *pa=ha->next;*pb=hb->next;*tc;
        hc=ha;       //将ha的头节点作为hc的头结点

        tc=hc;
        while (tc->next != NULL)
        {
            tc = tc->next;//让tc一直指向hc的尾节点
        }

        tc->next = hb;//连起来了

        free(hb);

第 7 楼

得分:0

另外说一下，你这函数传参hc是无法改变调用者的实际hc，要么用return返回，要么传参用SLinkNode **。
还有因为未申请新的堆空间，你用free(hb)，会将你新串联好的表后半部给回收了，导致异常。
如果书上就是这么写的，建议你赶紧换个书看，这书作者水平太次。

第 8 楼

得分:0

#include "stdio.h"
#include "stdlib.h"

typedef struct SLinkNode
{
    int value;
    struct SLinkNode *next;
} SLinkNode;

void erlu(SLinkNode *ha,SLinkNode *hb,SLinkNode **hc)
{
    SLinkNode *tc;
    *hc=ha;       //将ha的头节点作为hc的头结点

    tc=*hc;
    while (tc->next != NULL)
    {
        tc = tc->next;//让tc一直指向hc的尾节点
    }

    tc->next = hb;//连起来了

//    free(hb);


}

void main()
{
    int i;
    SLinkNode *a[8];
    SLinkNode *b[8];
    SLinkNode *c;

    for (i=0; i<8; i++)
    {
        a[i] = (SLinkNode *)malloc(sizeof(SLinkNode));
        a[i]->value = 8-i;
        if (i == 0)
        {
            a[i]->next = 0;
        }
        else
        {
            a[i]->next = a[i-1];
        }

        b[i] = (SLinkNode *)malloc(sizeof(SLinkNode));
        b[i]->value = 16-i;
        if (i == 0)
        {
            b[i]->next = 0;
        }
        else
        {
            b[i]->next = b[i-1];
        }
    }

    erlu(a[7], b[7], &c);

    for (i=0; i<16; i++)
    {
        printf("%d ", c->value);
        c = c->next;
    }
    printf("\n");
}