3485. 最大异或和

#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 100010, M = 31 * maxn;
int ch[maxn];
int n;
int son[M][2], idx = 0;
int cnt[M];//M一定要这么大
void insert(int x, int v)
{int p = 0;for (int i = 30; ~i; i--){int u = x >> i & 1;if (!son[p][u])son[p][u] = ++idx;p = son[p][u];cnt[p] += v;}
}
int search(int x)
{int p = 0;int ret = 0;for (int i = 30; ~i; i--){int u = x >> i & 1;if (cnt[son[p][!u]]){ret = ret * 2 + 1;p = son[p][!u];}else{ret = ret * 2;p = son[p][u];}}return ret;
}
int main()
{int m;cin >> n >> m;for (int i = 1; i <= n; i++){cin >> ch[i];ch[i] = ch[i] ^ ch[i - 1];}insert(ch[0], 1);int res = 0;for (int i = 1; i <= n; i++){if (i > m)insert(ch[i - m - 1], -1);res = max(res, search(ch[i]));insert(ch[i], 1);}cout << res;
}