hdu5798 Stabilization

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;
}