Codeforces 282E Sausage Maximization(字典树)

#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>

using namespace std;

typedef long long ll;
const int maxn = 1e5 + 5;

struct Tire {
int sz, g[maxn * 100][2];

void init();
void insert(ll s);
ll find(ll s);
}T;

int N;
ll A[maxn], prefix[maxn], suffix[maxn];

int main () {
scanf("%d", &N);
for (int i = 1; i <= N; i++)
scanf("%lld", &A[i]);

for (int i = 1; i <= N; i++)
prefix[i] = prefix[i-1] ^ A[i];
for (int i = N; i; i--)
suffix[i] = suffix[i+1] ^ A[i];

ll ans = 0;
T.init();

for (int i = N; i >= 0; i--) {
T.insert(suffix[i+1]);
ans = max(ans, T.find(prefix[i]));
}
printf("%lld\n", ans);
return 0;
}

void Tire::init() {
sz = 1;
memset(g[0], 0, sizeof(g[0]));
}

void Tire::insert(ll s) {
int u = 0;

for (int i = 60; i >= 0; i--) {
int v = (s>>i)&1;

if (g[u][v] == 0) {
memset(g[sz], 0, sizeof(g[sz]));
g[u][v] = sz++;
}
u = g[u][v];
}
}

ll Tire::find (ll s) {
int u = 0;
ll ret = 0;

for (int i = 60; i >= 0; i--) {
int v = ((s>>i)&1) ^ 1;

if (g[u][v])
ret |= (1LL<<i);
else
v = v ^ 1;
u = g[u][v];
}
return ret;
}