C语言一道题，大神分分钟搞定

#include
#include
typedef struct Char_{
char ch;
char intch;
struct Char_ *next;
}CHAR_;
int main(void)
{
CHAR_ *node = NULL;
CHAR_ *ch_ = NULL;
CHAR_ *hear = NULL;
char zimu = 'a';
char panduanzimu;
char record;
for (; zimu != 'e'; zimu++)
{
ch_ = (CHAR_ *)malloc(sizeof(CHAR_));
if (ch_ == NULL)
{
exit(0);
}

ch_->ch = zimu;
ch_->next = NULL;
if (node == NULL)
{
node = ch_;
}
else{
node->next = ch_;
node = node->next;
}
if (hear == NULL)
{
hear = node;
}
}
for (zimu -= 2; zimu != ('a' - 1); zimu--)
{
ch_ = (CHAR_ *)malloc(sizeof(CHAR_));
if (ch_ == NULL)
{
exit(0);
}
ch_->ch = zimu;
ch_->next = NULL;
node->next = ch_;
node = node->next;
}
for (node = hear, zimu = '0'; node != NULL; node = node->next, zimu++)
{
node->intch = zimu;
}
scanf("%c", &panduanzimu);
node = hear;
if (panduanzimu >= '0'&&panduanzimu <= '6')
{
while (node != NULL)
{
if (panduanzimu == node->intch)
{
printf("%c", node->ch);
break;
}
node = node->next;
}
}
else if (panduanzimu >= 'a'&&panduanzimu <= 'd')
{
while (node != NULL)
{
if (panduanzimu == node->ch)
{
record = node->intch;
}
node = node->next;
}
printf("%c", record);
}
else{
printf("N");
}
node = hear;
while (node != NULL)
{
hear = node->next;
free(node);
node = hear;
}
return 0;
}