(全国多校重现赛一) H Numbers

zk has n numbers a1,a2,...,ana1,a2,...,an. For each (i,j) satisfying 1≤i<j≤n, zk generates a new number (ai+aj)(ai+aj). These new numbers could make up a new sequence b1，b2,...,bn(n−1)/2b1，b2,...,bn(n−1)/2.

LsF wants to make some trouble. While zk is sleeping, Lsf mixed up sequence a and b with random order so that zk can't figure out which numbers were in a or b. "I'm angry!", says zk.

Can you help zk find out which n numbers were originally in a?

Input

Multiple test cases(not exceed 10).

For each test case:

∙∙The first line is an integer m(0≤m≤125250), indicating the total length of a and b. It's guaranteed m can be formed as n(n+1)/2.

∙∙The second line contains m numbers, indicating the mixed sequence of a and b.

Each aiai is in [1,10^9]

Output

For each test case, output two lines.

The first line is an integer n, indicating the length of sequence a;

The second line should contain n space-seprated integers a1,a2,...,an(a1≤a2≤...≤an)a1,a2,...,an(a1≤a2≤...≤an). These are numbers in sequence a.

It's guaranteed that there is only one solution for each case.

Sample Input

6

2 2 2 4 4 4

21

1 2 3 3 4 4 5 5 5 6 6 6 7 7 7 8 8 9 9 10 11

Sample Output

3

2 2 2

6

1 2 3 4 5 6

这个看代码吧。QAQ

#include<bits/stdc++.h>

using namespace std;

const int maxn=1e5+5;

int n,m;

vector <int> a,b,c,ans;

map <int,int> mmp;

int main()

{

	while(~scanf("%d",&n))

	{

		a.clear();

		b.clear();

		c.clear();

		ans.clear();

		mmp.clear();

		int temp;

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

		{

			scanf("%d",&temp);

			a.push_back(temp);

			if(mmp[temp]==0) mmp[temp]=1;

			else mmp[temp]++; 

		}

		sort(a.begin(),a.end());

		ans.push_back(a[0]);

		for(int i=1;i<n;i++)

		{

			if(mmp[a[i]]==0) continue;

			for(int j=0;j<ans.size();j++)

			{

				mmp[ans[j]+a[i]]--;

			}

			ans.push_back(a[i]);

			mmp[a[i]]--;

		}

		printf("%d\n",ans.size());

		vector <int> ::iterator it;

		for(it=ans.begin();it!=ans.end();it++)

		{

			if(it==ans.begin()) cout<<*it;

			else cout<<" "<<*it;

		}

		cout<<endl;

	}

	return 0;

}

巴特西

(全国多校重现赛一) H Numbers

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