CSES – Two Sets II

#include<bits/stdc++.h>
#define int long long
#define fastio ios_base::sync_with_stdio(0);cin.tie(0)
using namespace std;
//declare
const int maxn = 2e5, mod = 1e9+7;
int n;
int dp[maxn];
//
signed main(){
    fastio;
    cin>>n;
    if(n*(n+1) % 4) return cout<<0<<"\n", 0;
    dp[0] = 1;
    int sum = n*(n+1)/4;
    for(int i=1;i<n;i++){
        for(int j=sum;j>=0;j--){
            if(j-i >= 0){
                (dp[j] += dp[j-i]) %= mod;
            }
        }
    }
    cout<<dp[sum]<<"\n";
    return 0;
}