大华2014校园招聘面试题链式存储串的连接操作

#include <stdio.h>

#define N   4

typedef struct Block
{
   char buffer[N];
   struct Block *next;
}Block;

typedef struct
{
       Block *head;
       Block *tail;
    int  len;
}BLString;


void BLStringAppend(BLString* s1, BLString* s2)
{
    if(NULL == s1 || NULL == s2)//参数无效
        return;
    if(NULL == s1->head && NULL == s2->head)//链表都为空
        return;
    if(NULL == s1->head && NULL != s2->head)
    {
        s1->head = s2->head; //直接串2的头赋值给串1的头指针
        return;
    }
    
    s1->tail->next = s2->head;//先将s2的头和s1的尾相连接

    Block *cur_node = s1->tail;
    Block *pnode = s2->head;
    int cur_len = strlen(cur_node);
    int i;
    while(pnode != s2->tail)
    {
        for(i = 0; i <  N - cur_len; i++)
        {
            cur_node->buffer[cur_len+ i] = pnode->buffer[i];
        }
        for(i = 0; i < cur_len; i++)
        {
            pnode->buffer[i] = pnode->buffer[i+cur_len];
        }
        cur_node = pnode;
        pnode = pnode->next;
    }
    
    int tail_len = strlen(s2->tail->buffer);
    if(tail_len < cur_len)
    {
        for(i = 0; i < tail_len; i++)
        {
            cur_node->buffer[cur_len+ i] = pnode->buffer[i];
        }
        cur_node->buffer[cur_len+i] = '\0';
        s1->tail = cur_node;
        cur_node->next = NULL;

        free(pnode);
    }
    else{
        for(i = 0; i <  N - cur_len; i++)
        {
            cur_node->buffer[cur_len+ i] = pnode->buffer[i];
        }
        for(i = 0; i < tail_len-(N-cur_len); i++)
        {
            pnode->buffer[i] = pnode->buffer[i+cur_len];
        }
        pnode->buffer[i] = '\0';
    }
}