Good Array CodeForces - 1077C

因为要计算数组总和所以这题int会爆，要用long long，坑！！！！

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
using namespace std;
typedef long long ll;
const int maxn=2e6+6;
ll a[maxn],b[maxn],num[maxn],sum,ans[maxn];
int main() {
  ll n;
  cin>>n;
  for(ll i=1; i<=n; i++) {
    cin>>a[i];
    b[i]=a[i];
    num[a[i]]++;
    sum+=a[i];
  }
  ll cnt=0;
  sort(b+1,b+1+n);
  for(ll i=1; i<=n; i++) {
    ll summ=sum-a[i];
    if(b[n]==a[i]&&num[a[i]]==1) {
      if(b[n-1]==summ-b[n-1])ans[++cnt]=i;
    } else if(b[n]==summ-b[n])ans[++cnt]=i;

  }
  cout<<cnt<<endl;
  for(ll i=1; i<=cnt; i++)
    cout<<ans[i]<<" ";
  cout<<endl;
}