CodeForces——1077 D. Cutting Out（二分答案）

题目链接

解题思路：
直接从众多“个数”中挑选满足答案的可能有很多。。。题目的限制条件是“find such array t that you can cut out the copy of t from s maximum number of times.” 所以要先二分找一个最大的amount，有了这个amount再去找k个满足的“个数”就可以啦

/* * @Author: Achan * @Date: 2018-11-17 00:21:36 * @Last Modified by: Achan * @Last Modified time: 2018-11-17 17:38:08 */
#include
using namespace std;
const int maxn = 2e5+2;

void read(int &x)
{
    x=0;int f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    x*=f;return;
}

int n,k,t;    
int a[maxn]; //个数
 
bool OK(int m)
{
	int res = 0; 
	for(int i = 1; i <=(int)2e5 ; i++)
	{
		if(a[i] < m) continue;
		res += a[i]/m;
	} 
	return res >= k; 
}

int main(void)
{
	read(n), read(k);
	for(int i = 0; i<n;i++) read(t),a[t]++;
	int l = 1;
	int r = n; 
	int mid , amount = 1; //在满足k个数的前题下，最大能进行的次数 
	while(l <= r)  //二分答案 （答案区间：1 ~ n） 
	{
		mid = (l+r)>>1; 	 
		OK(mid) ? amount = mid, l = mid + 1 : r = mid - 1; 
	}
 	// cout<
	vector <int> ans(k);    
	int tot = 0;
	for(int i = 1; i<=(int)2e5 ;i++)
	{
		if(a[i] < amount) continue; 
		for(int j = 1;j <= a[i]/amount; j++)
			{
				ans[tot++] = i;
				if(tot == k) 
				{
					i = (int )2e5 + 1; 
					break;
				}
			}
	}
	while(k--) printf("%d ",ans[k]);   
	puts("");
}

D. Cutting Out
time limit per test
3 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

You are given an array s
consisting of n

integers.

You have to find any array t
of length k such that you can cut out maximum number of copies of array t from array s

.

Cutting out the copy of t
means that for each element ti of array t you have to find ti in s and remove it from s. If for some ti you cannot find such element in s, then you cannot cut out one more copy of t

. The both arrays can contain duplicate elements.

For example, if s=[1,2,3,2,4,3,1]
and k=3 then one of the possible answers is t=[1,2,3]. This array t can be cut out 2

times.

To cut out the first copy of t

you can use the elements [1,2––,3,2,4,3––,1––] (use the highlighted elements). After cutting out the first copy of t the array s can look like [1,3,2,4]
.
To cut out the second copy of t
you can use the elements [1––,3––,2––,4]. After cutting out the second copy of t the array s will be [4]

. 

Your task is to find such array t
that you can cut out the copy of t from s

maximum number of times. If there are multiple answers, you may choose any of them.
Input

The first line of the input contains two integers n
and k (1≤k≤n≤2⋅105) — the number of elements in s and the desired number of elements in t

, respectively.

The second line of the input contains exactly n
integers s1,s2,…,sn (1≤si≤2⋅105

).
Output

Print k
integers — the elements of array t such that you can cut out maximum possible number of copies of this array from s. If there are multiple answers, print any of them. The required array t can contain duplicate elements. All the elements of t (t1,t2,…,tk) should satisfy the following condition: 1≤ti≤2⋅105

.
Examples
Input
Copy

7 3
1 2 3 2 4 3 1

Output
Copy

1 2 3

Input
Copy

10 4
1 3 1 3 10 3 7 7 12 3

Output
Copy

7 3 1 3

Input
Copy

15 2
1 2 1 1 1 2 1 1 2 1 2 1 1 1 1

Output
Copy

1 1

Note

The first example is described in the problem statement.

In the second example the only answer is [7,3,1,3]
and any its permutations. It can be shown that you cannot choose any other array such that the maximum number of copies you can cut out would be equal to 2

.

In the third example the array t
can be cut out 5

times.