24pts求教（月赛调了半天难绷

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 2e5 + 5;
int a[N], pre[N];
vector<int> last[2];

bool chk(int n, int m, int t) {
    vector<vector<bool>> dp(m+1, vector<bool>(n+1, false));
    vector<int> pref(n+1, 0);
    for(int i=1; i<=n; i++) pref[i] = pref[i-1] ^ a[i];
    
    dp[0][0] = true;
    for(int k=1; k<=m; k++) {
        for(int i=k; i<=n; i++) {
            for(int j=k; j<=i; j++) {
                int seg_xor = pref[i] ^ pref[j-1];
                if((seg_xor & t) == t && dp[k-1][j-1]) {
                    dp[k][i] = true;
                    break;
                }
            }
        }
    }
    return dp[m][n];
}


int main() {
    int T;
    scanf("%d", &T);
    while (T--) {
        int n, m;
        scanf("%d%d", &n, &m);
        for(int i = 1; i <= n; ++i) scanf("%d", &a[i]);
        
        int ans = 0;
        for (int i = 30; i >= 0; --i) {
            int target = ans | (1 << i);
            if (chk(n, m, target)) {
                ans = target;
            }
        }
        printf("%d\n", ans);
    }
    return 0;
}