codeforces 282E. Sausage Maximization Trie

#include <iostream>
#include <vector>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <string>
#include <queue>
#include <stack>
#include <bitset>
using namespace std;
#define pb(x) push_back(x)
#define ll long long
#define mk(x, y) make_pair(x, y)
#define lson l, m, rt<<1
#define mem(a) memset(a, 0, sizeof(a))
#define rson m+1, r, rt<<1|1
#define mem1(a) memset(a, -1, sizeof(a))
#define mem2(a) memset(a, 0x3f, sizeof(a))
#define rep(i, n, a) for(int i = a; i<n; i++)
#define fi first
#define se second
typedef pair<int, int> pll;
const double PI = acos(-1.0);
const double eps = 1e-8;
const int mod = 1e9+7;
const int inf = 1061109567;
const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
struct Trie
{
    Trie *next[2];
    Trie() {
        next[0] = next[1] = NULL;
    }
};
ll num[100005], top = 40;
Trie *root = new Trie();
void add(ll val) {
    Trie *p = root;
    for(int i = top-1; i>=0; i--) {
        int tmp = val>>i&1;
        if(!p->next[tmp])
            p->next[tmp] = new Trie();
        p = p->next[tmp];
    }
}
ll query(ll val) {
    Trie *p = root;
    ll ret = 0;
    for(int i = top-1; i>=0; i--) {
        int tmp = val>>i&1;
        if(p->next[tmp^1]) {
            ret |= 1LL<<i;
            tmp ^=1;
        }
        p = p->next[tmp];
    }
    return ret;
}
int main()
{
    int n;
    ll prefix = 0, suffix = 0, ans = 0;
    cin>>n;
    for(int i = 1; i<=n; i++) {
        cin>>num[i];
        suffix^=num[i];
    }
    for(int i = 1; i<=n+1; i++) {
        add(prefix);
        ans = max(ans, query(suffix));
        if(i<=n) {
            prefix^=num[i];
            suffix^=num[i];
        }
    }
    cout<<ans<<endl;
    return 0;
}