A

只要两个数不一样就需要移动，发现如果要全改为众数的话，无论众数是最大值还是最小值都不如直接默认改为中位数最优。

$AC Code:$

#include<iostream>
#include<queue>
#include<deque>
#include<bitset>
#include<string>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<unordered_map>
#include<set>
#include<map>
#include<ctime>
#include<random>
#include<vector>
#include<utility>
#define f(i,a,b) for(ll i=a;i<=b;i++)
using ll = long long;
using db = double;
ll rd(){ll x=0,w=1;char c=getchar();while(c<'0'||c>'9'){if(c=='-'){w=-1;}c=getchar();}while('0'<=c&&c<='9'){x=x*10+(c-'0');c=getchar();}return x*w;}
using namespace std;
const ll MX =2e5+7;
const ll mod = 998244353;
mt19937 mrd(time(0));
namespace Wunsch{

    ll n,T,k,m,ans,cnt,nm;
    ll a[MX];

    void work(){
        n=rd();
        f(i,1,n)a[i]=rd();
        sort(a+1,a+1+n);
        f(i,1,(n>>1)){
            if(a[i]!=a[n-i+1])cnt++;
        }
        cout<<cnt<<"\n";
        cnt=0;
        return ;
    }

    bool main(){
        T=rd();
        // T=1;
        while(T--)work();
        return 1;
    }
}
bool amiya=Wunsch::main();
int main(){;}

B

发现每个数只对其后面有影响，也就是说答案数列是单调不增的，只需要判断每次加进来的数是否会让答案变小即可。

$AC Code:$

#include<iostream>
#include<queue>
#include<deque>
#include<bitset>
#include<string>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<unordered_map>
#include<set>
#include<map>
#include<ctime>
#include<random>
#include<vector>
#include<utility>
#define f(i,a,b) for(ll i=a;i<=b;i++)
using ll = long long;
using db = double;
ll rd(){ll x=0,w=1;char c=getchar();while(c<'0'||c>'9'){if(c=='-'){w=-1;}c=getchar();}while('0'<=c&&c<='9'){x=x*10+(c-'0');c=getchar();}return x*w;}
using namespace std;
const ll MX =2e5+7;
const ll mod = 998244353;
mt19937 mrd(time(0));
namespace Wunsch{

    ll n,T,k,m,ans,cnt,nm;
    ll a[MX];

    void work(){
        n=rd();
        ans=1e9+7;
        f(i,1,n){
            a[i]=rd();
            cnt+=a[i];
            ans=min(ans,cnt/i);
            cout<<ans<<" ";
        }
        cout<<"\n";
        cnt=0;
        return ;
    }

    bool main(){
        T=rd();
        // T=1;
        while(T--)work();
        return 1;
    }
}
bool amiya=Wunsch::main();
int main(){;}

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