ソースコード
#include<iomanip>
#include<limits>
#include<thread>
#include<utility>
#include<iostream>
#include<string>
#include<algorithm>
#include<set>
#include<map>
#include<vector>
#include<stack>
#include<queue>
#include<cmath>
#include<numeric>
#include<cassert>
#include<random>
#include<chrono>
#include<unordered_map>
#include<list>
using namespace std;
typedef unsigned long long int ull;
typedef long long int ll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pi;
typedef pair<double,double> pd;
typedef pair<double,ll> pdl;
#define F first
#define S second
#define MK make_pair
const ll E=1e18+7;
const ll MOD=1000000007;
int main(){
ll n;
cin>>n;
vector<ll> a;
for(int i=0;i<n;i++){
ll b;
cin>>b;
a.push_back(b);
}
sort(a.begin(),a.end());
vector<ll> dp(n,0);
dp[0]=1;
ll ans=1;
for(int i=1;i<n;i++){
if(a[i]==a[i-1]){
ans+=dp[i-1];
dp[i]=dp[i-1];
}
else{
dp[i]=ans;
ans+=ans;
}
}
cout<<ans<<endl;
return 0;
}