#include <bits/stdc++.h>
using namespace std;
vector<int> add(vector<int> &A, vector<int> &B)  // C = A + B, A >= 0, B >= 0
{
  if (A.size() < B.size()) return add(B, A);

  vector<int> C;
  int t = 0;
  for (int i = 0; i < A.size(); i ++ )
  {
    t += A[i];
    if (i < B.size()) t += B[i];
    C.push_back(t % 10);
    t /= 10;
  }

  if (t) C.push_back(t);
  return C;
}
vector<int> sub(vector<int> &A, vector<int> &B)  // C = A - B, 满足A >= B, A >= 0, B >= 0
{
  vector<int> C;
  for (int i = 0, t = 0; i < A.size(); i ++ )
  {
    t = A[i] - t;
    if (i < B.size()) t -= B[i];
    C.push_back((t + 10) % 10);
    if (t < 0) t = 1;
    else t = 0;
  }

  while (C.size() > 1 && C.back() == 0) C.pop_back();
  return C;
}

int main()
{
  vector<int> a,s,u,p;
  for(int i=1; i<=100000; i++)
    a.push_back(i);
  srand(time(0));
  random_shuffle(a.begin(),a.end());
  for(int i=1; i<=50; i++)
  {
    if(i==50)cout<<a[i];
    else cout<<a[i]<<"+";
    u.push_back(a[i]);
    reverse(s.begin(),s.end());
    reverse(u.begin(),u.end());
    s=add(s,u);
    reverse(s.begin(),s.end());
    u=p;
  }
  cout<<endl;
  for(int i=0; i<s.size(); i++)cout<<s[i];
  return 0;
}
返回的是结果