#include<cstdio>
#include<cstring>
using namespace std;
int *str2int(char *str)
  {
      int i ,len=strlen(str);
      int *a=new int [(len+1)*sizeof(int)];
      for(i=0;i<len;i++)
      a[i]=(int)str[len-i-1]-48;
      return a;
  }
  int check(int *a,int n)
  {
      int k=0,len=n;
      while(a[len-1]==0&&len>1)
      len--;
      for(k=0;k<len;k++)
      {
          if(a[k]>=10)
          {
              a[k+1]=a[k+1]+a[k]/10;
              a[k]=a[k]%10;
          }
      }
      if(a[k]!=0)
      len=k+1;
      return len;
  }
  char *int2str(int *a,int n)
  {
      int i;
      char *str=new char[(n+1)*sizeof(char)];
      for(i=0;i<n;i++)
      str[i]=(char)a[n-i-1]+48;
      str[n]='\0';
      return str;

  }
  char *addition(char *m1,char *m2)
  {
      int i,len1,len2;
      int *t1,*t2;
      len1=strlen(m1);
      len2=strlen(m2);
      int len=(len1>len2)?len1:len2;
      t1=new int[(len+2)*sizeof(int)];
      t2=new int[(len+2)*sizeof(int)];
      t1=str2int(m1);
      t2=str2int(m2);
      for(i=len1;i<len+1;i++)
      t1[i]=0;
      for(i=len2;i<len+1;i++)
      t2[i]=0;
      for(i=0;i<len;i++)
      t1[i]=t1[i]+t2[i];
      len=check(t1,len);
      return int2str(t1,len);
  }
  int main()
  {
      char s1[1010],s2[1010];
      int n;
      int m=0;
      scanf("%d",&n);
      while(n--)
      {
          scanf("%s%s",s1,s2);
          printf("case %d:\n",++m);
          printf("%s + %s = %s\n",s1,s2,addition(s1,s2));
      }
      return 0;
}
这是大数加法的一道acm题，
提交后为什么是system error
请教各位大神