Educational Codeforces Round 21 D. Array Division

#include<bits/stdc++.h>

using namespace std;

#define X first
#define Y second
#define eps  1e-2
#define gcd __gcd
#define pb push_back
#define PI acos(-1.0)
#define lowbit(x) (x)&(-x)
#define bug printf("!!!!!\n");
#define mem(x,y) memset(x,y,sizeof(x))

typedef long long LL;
typedef long double LD;
typedef pair<int,int> pii;
typedef unsigned long long uLL;

#define int long long 
const int maxn = 1e5+2;
const int INF  = 1<<30;
const int mod  = 1e9+7;

int n,a[maxn],b,c,d;
map<int,int> mp,mp2;

void solve(){
    scanf("%lld",&n);
    for(int i=1;i<=n;i++){scanf("%lld",&a[i]);d+=a[i];}
    if(d%2==1){cout<<"NO"<<endl;return ;}
    d=d/2;int fl=0;
    mp[0]=mp2[0]=1;
    for(int i=1;i<=n;i++){
        b+=a[i];
        if(mp[d-a[i]]==1) fl=1;
        mp[b]=1;
    }
    for(int i=n;i>=1;i--){
        c+=a[i];
        if(mp2[d-a[i]]==1) fl=1;
        mp2[c]=1;
    }
    if(fl==1) cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
    return;
}

int32_t main()
{
//    freopen("in.txt","r",stdin);
//    freopen("out.txt","w",stdout);
//    ios::sync_with_stdio(false);
    int t = 1;
    //scanf("%d",&t);
    while(t--){
    //    printf("Case %d: ",cas++);
        solve();
    }
    return 0;
}