//实现输入任意两个若干位的整数，进行加法，计算并返回加和后的结果。
//（注意两个整数可以足够大，以至于double都会溢出。只要系统内存够用，
//此加法都要正常运行）
#include"stdio.h"
#include"stdlib.h"
typedef struct node{
  int x;
  struct node *next;
  struct node *before;
}llnode;

int charToNumber(char c)
{
  return c-48;
}

void getNumber(llnode* tail)
{
  char c;
  llnode *p;
  llnode *q;
  q = tail;
  printf("请输入一个整数， 输入完成后敲击回车:");
  while(1)
    {
      c = getchar();
      if(c == '\n')
	{
	  break;
	}
      else
	{
	  p = (llnode *)malloc(sizeof(llnode));
	  p->x = charToNumber(c);
	  p->before = NULL;
	  if(tail->x == 0)
	    {
	      tail->before = p;
	      p->next = tail;
	      tail->x = tail->x+1;
	    }
	  else
	    {
	      q = tail->before;
	      q->next = p;
	      p->before = q;
	      p->next = tail;
	      tail->before = p;
	      q = p;
	      tail->x = tail->x+1;
	    }
	}
    }
}

void addNumber(llnode* ctail, llnode* atail, llnode* btail)
{
  int i=0;
  int alength = atail->x;
  int blength = btail->x;
  llnode *pshort;
  llnode *plong;
  llnode *ps;
  llnode *pl;
  llnode *p;
  llnode *q;
  int a;
  int b;
  int nextc;
  int thisc;
  int d;
  if(alength>blength)
    {
      pshort = btail;
      plong = atail;
    }
  else
    {
      pshort = atail;
      plong = btail;
    }
  ps = pshort->before;
  pl = plong->before;
  while(i<pshort->x)
    {
      thisc = nextc;
      if(ps->x + pl->x >=10)
	{
	  nextc = 1;
	  d = (ps->x + pl->x)%10;
	}
      else
	{
	  nextc = 0;
	  d = (ps->x + pl->x);
	}
      ps = ps->before;
      pl = pl->before;
      p = (llnode *)malloc(sizeof(llnode));
      p->x = d+thisc; 
      p->before = NULL;
      if(ctail->x == 0)
	{
	  ctail->before = p;
	  p->next = ctail;
	  ctail->x = ctail->x+1; 
	  q = p;
	}
      else
	{
	  p->next = q;
	  q->before = p;
	  q = p;
	  ctail->x = ctail->x+1;
	}
      i = i+1;
    }
  while(i<plong->x)
    {
      if(i == pshort->x)
	{
	  p = (llnode *)malloc(sizeof(llnode));
      	  p->x = (pl->x)+nextc; 
      	  p->before = NULL;
      	}
      else
      	{
	  p = (llnode *)malloc(sizeof(llnode));
      	  p->x = pl->x;
	  p->before = NULL;
      	}
      p->next = q;
      q->before = p;
      q = p;
      ctail->x = ctail->x+1;
      pl = pl->before;
      i = i+1;
    }
}

void showResult(llnode* ctail)
{
  llnode *p;
  p = ctail;
  while(p->before != NULL)
    {
      p = p->before;
    }
  while(p != ctail)
    {
      printf("%d",p->x);
      p = p->next;
    }
  printf("\n");
}

int main()
{
  llnode *atail = (llnode *)malloc(sizeof(llnode));
  llnode *btail = (llnode *)malloc(sizeof(llnode));
  llnode *ctail = (llnode *)malloc(sizeof(llnode));
  llnode *p=atail;
  atail->x = 0;
  btail->x = 0;
  ctail->x = 0;
  atail->next = NULL;
  btail->next = NULL;
  ctail->next = NULL;
  getNumber(atail);
  getNumber(btail);
  addNumber(ctail, atail, btail);
  showResult(ctail);
  return 1;
}