一道极其简单的ACM题,为什么第2段代码通不过测试?
http://acm.hziee.edu.cn/showproblem.php?pid=1096
题目
Your task is to calculate the sum of some integers.

Input
Input contains an integer N in the first line, and then N lines follow. Each line starts with a integer M, and then M integers follow in the same line.

Output
For each group of input integers you should output their sum in one line, and you must note that there is a blank line between outputs.

Sample Input
3
4 1 2 3 4
5 1 2 3 4 5
3 1 2 3

Sample Output
10
15
6

第一段代码,通过测试
# include <iostream>
using namespace std;
int main()
{
 int m,n,s;
 int sum;
 cin>>n;
 for(int i=0;i<n;i++)
 {
  if(i)
   cout<<endl;
  cin>>m;
  sum=0;
  for(int j=0;j<m;j++)
  {
   cin>>s;
   sum+=s;
  }
  cout<<sum<<endl;
 }
 return 0;
}

第2段代码,通不过测试,why?
#include <iostream>
#include <vector>
#include <numeric>
#include <string>
#include <sstream>
using namespace std;
int main(void)
{
int times;
cin>>times;
while(times--!=-1){
        string str;
        istringstream istr;
        int temp;

        getline(cin,str);
        istr.str(str);
        vector<int> array;
       
        bool ignore=true;
        while(!istr.eof()){
           istr>>temp;                          
           if(ignore==true) {ignore=false;continue;}     
           array.push_back(temp);
           }
        if(!array.empty()) cout<<accumulate(array.begin(), array.end(),0)<<"\n"<<endl;   
 }

return 0;
}

有时候第2段代码会得出奇怪的结果,这是为什么?