Codeforces Round #638 (Div. 2)

链接 https://codeforces.com/contest/1348

A. Phoenix and Balance

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int maxn=1e5+5,maxm=1e5+5;
const int mod=1e9+7,inf=0x7f7f7f7f;

int t,n;

int main()
{
	cin>>t;
	while(t--)
	{
		cin>>n;
		ll ans1=0,ans2=0;
		for(int i=1;i<=n/2-1;++i)
			ans1+=(1<<i);
		ans1+=(1<<n);
		for(int i=n/2;i<=n-1;++i)
			ans2+=(1<<i);
		cout<<ans1-ans2<<"\n";	
	}
	return 0;
}

B. Phoenix and Beauty

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int maxn=100+5,maxm=1e5+5;
const int mod=1e9+7,inf=0x7f7f7f7f;

int t,n,k;
int a[maxn];

int main()
{
    cin>>t;
    while(t--)
    {
        cin>>n>>k;
        set<int> s;
        for(int i=1;i<=n;++i)
            cin>>a[i],s.insert(a[i]);
        if(s.size()>k)
        {
            puts("-1");
            continue;
        }
        else if(s.size()<k)
        {
            for(int i=1;i<=n;++i)
            {
                s.insert(i);
                if(s.size()==k)
                    break;
            }
        }
        vector<int> ans;
        for(auto i : s)
            ans.push_back(i);

        for(int i=2;i<=n;++i)
        {
            int p=(int)ans.size()-k;
            if(a[i]==ans[p])
                ans.push_back(a[i]);
            else
                ans.push_back(ans[p]),--i;
        }
        cout<<(int)ans.size()<<"\n";
        for(auto i : ans)
            cout<<i<<" ";
        cout<<"\n";
    }
	return 0;
}

C. Phoenix and Distribution

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int maxn=1e5+5,maxm=1e5+5;
const int mod=1e9+7,inf=0x7f7f7f7f;

int t,n,k;
string s;

int main()
{
	cin>>t;
	while(t--)
	{
		cin>>n>>k>>s;
		sort(s.begin(),s.end());
		s="0"+s;
		string ans="";
		if(s[1]==s[k])
		{
			ans=s[1];
			if(s[k+1]==s[n])
			{
				int cnt=n/k+(n%k?1:0)-1;
				for(int i=1;i<=cnt;++i)
					ans+=s[k+1];	
			}
			else
			{
				for(int i=k+1;i<=n;++i)
					ans+=s[i];
			}
		}
		else
			ans=s[k];
		cout<<ans<<"\n";	
	}
	return 0;
}

D. Phoenix and Science

直接构造 1+2+4+8+16+x=n。最后将这些数排个序，然后输出差分数组

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int maxn=1e5+5,maxm=1e5+5;
const int mod=1e9+7,inf=0x7f7f7f7f;

int t,n;

int main()
{
	cin>>t;
	while(t--)
	{
		cin>>n;
		vector<int> ans;
		for(int i=1;i<=n;i*=2)
		{
			ans.push_back(i);
			n-=i;	
		}
		if(n>0)
		{
			ans.push_back(n);
			sort(ans.begin(),ans.end());
		}
		int n=(int)ans.size()-1;
		cout<<n<<"\n";
		for(int i=1;i<=n;++i)
			cout<<ans[i]-ans[i-1]<<" ";
		cout<<"\n";
	}
	return 0;
}

每次加入数组的数是$min(n/2,ans.back()\ast 2)$

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int maxn=1e5+5,maxm=1e5+5;
const int mod=1e9+7,inf=0x7f7f7f7f;

int t,n;

int main()
{
	cin>>t;
	while(t--)
	{
		cin>>n;
		vector<int> ans;
		ans.push_back(1);
		n--;
		while(1)
		{
			if(2*ans.back()>=n)
			{
				ans.push_back(n);
				break;
			}
			ans.push_back(min(n/2,ans.back()*2));
			n-=ans.back();
		}
		
		int n=(int)ans.size()-1;
		cout<<n<<"\n";
		for(int i=1;i<=n;++i)
			cout<<ans[i]-ans[i-1]<<" ";
		cout<<"\n";
	}
	return 0;
}

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int maxn=1e5+5,maxm=1e5+5;
const int mod=1e9+7,inf=0x7f7f7f7f;

int t,n;

int main()
{
	cin>>t;
	while(t--)
	{
		cin>>n;
		vector<int> ans;
		ans.push_back(1);
		int cur=1;
		n--;
		while(cur*4<=n)
		{
			cur*=2;
			n-=cur;
			ans.push_back(cur);
		}
		
		if(cur*2>=n)
			ans.push_back(n);
		else
			ans.push_back(n/2),ans.push_back(n-n/2);
		int cnt=ans.size()-1;
		cout<<cnt<<"\n";
		for(int i=1;i<=cnt;++i)
			cout<<ans[i]-ans[i-1]<<" ";
		cout<<"\n";		
	}
	return 0;
}