温习一下多校的题目
这题主要抓住一点,亦或值的贡献是固定的
所以按位搜索即可

#include<bits/stdc++.h>

using namespace std;

typedef long long ll;

const int MAXN = 1e5+5;

int n;

int A[MAXN];

ll cnt[20][20];

int d[20];

int X;

int Ed;

ll ans;

void dfs(int pos,int x,ll num){

    if(num > ans) return;

    if(pos == Ed){

        if(num < ans) { ans = num; X = x; }

        else if(num == ans && X > x) X = x;

        return;

    }

    int i = pos;

    for(d[i] = 0; d[i] < 2; d[i] ++){

        ll tmp = num + cnt[i][i];

        for(int j = 0; j < i; ++j)

            if(d[i] ^ d[j])

                tmp -= cnt[i][j];

            else tmp += cnt[i][j];

        dfs(pos+1, x|d[i]<<i, tmp);

    }

}

int main(){

    int T; scanf("%d",&T);

    while(T--){

        memset(cnt,0,sizeof(cnt));

        scanf("%d",&n);

        for(int i = 1; i <= n; ++i) scanf("%d",&A[i]);

        for(int i = 2; i <= n; ++i) {

            int t1 = A[i-1]; int t2 = A[i];

            int high = 20;

            while(high>=0 && ~(t1^t2)>>high&1 ) high--;

        //    printf("%d\n",high);

            int mx = max(t1, t2);

            int mi = min(t1, t2);

            for(int j = high; j >= 0; --j){

                cnt[high][j] += (mx&1<<j) - (mi&1<<j);

            }

        }

        Ed = 20;

        for(; Ed >0; Ed--)

            if(cnt[Ed-1][Ed-1]) break;

        X=0; ans=1e18;

        dfs(0,0,0);

        printf("%d %lld\n",X,ans);

    }

    return 0;

}