rt,只过了样例。求大佬来调。

#include <bits/stdc++.h>

#define BAR cout<<"*******\n";
#define fst first
#define snd second
#define INFILE(x) freopen(x,"r",stdin)
#define OUTFILE(x) freopen(x,"w",stdout)
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3f
using namespace std;
using ll = long long;
using ul = unsigned long long;
using ui = unsigned int;
using db = double;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pll = pair<ll, ll>;
using puu = pair<unsigned, unsigned>;
const int max_n = 5e5 + 10;
unsigned xor_sum[max_n];

struct {
    struct node {
        int next[2]{}, cnt = 0;
    } nodes[max_n * 2 * 32];
    int t = 0;

    void insert(unsigned x) {
        unsigned p = 0;
        for (unsigned mask = 1 << 31; mask; mask >>= 1) {
            ++nodes[p].cnt;
            bool c = x & mask;
            if (!nodes[p].next[c]) nodes[p].next[c] = ++t;
            p = nodes[p].next[c];
        }
        ++nodes[p].cnt;
    }

    unsigned nth_xor(unsigned x, unsigned n) {
        unsigned p = 0, ans = 0, gt_cnt = 0;
        --n;
        for (unsigned mask = 1 << 31; mask; mask >>= 1) {
            bool c = x & mask;
            if (!nodes[p].next[c]) {
                p = nodes[p].next[!c];
                ans |= mask;
                continue;
            }
            if (!nodes[p].next[!c]) {
                p = nodes[p].next[c];
                continue;
            }
            if (gt_cnt + nodes[p].next[!c] > n) {
                p = nodes[p].next[!c];
                ans |= mask;
            } else {
                gt_cnt += nodes[p].next[!c];
                p = nodes[p].next[c];
            }
        }
        return ans;
    }
} trie;

int calc_cnt[max_n];

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n, k;
    cin >> n >> k;
    xor_sum[0] = 0;
    for (int i = 1; i <= n; ++i) {
        int a;
        cin >> a;
        xor_sum[i] = xor_sum[i - 1] ^ a;
        trie.insert(xor_sum[i]);
    }
    priority_queue<puu> q;
    ll ans = 0;
    for (int i = 1; i <= n; ++i) {
        ++calc_cnt[i];
        q.emplace(trie.nth_xor(xor_sum[i], 1), i);
    }
    for (int i = 1; i <= k << 1; ++i) {
        auto t = q.top();
        ans += t.fst;
        ++calc_cnt[t.snd];
        q.emplace(trie.nth_xor(xor_sum[t.snd], calc_cnt[t.snd]), t.snd);
    }
    cout << (ans >> 1) << '\n';
    return 0;
}