You are given an array a of length n consisting of integers. You can apply the following operation, consisting of several steps, on the array a zero or more times:
you select two different numbers in the array ai and aj;
you remove i-th and j-th elements from the array.
For example, if n=6 and a=[1,6,1,1,4,4], then you can perform the following sequence of operations:
select i=1,j=5. The array a becomes equal to [6,1,1,4];
select i=1,j=2. The array a becomes equal to [1,4].
What can be the minimum size of the array after applying some sequence of operations to it?
Input
The first line contains a single integer t (1≤t≤104). Then t test cases follow.
The first line of each test case contains a single integer n (1≤n≤2⋅105) is length of the array a.
The second line of each test case contains n integers a1,a2,…,an (1≤ai≤109).
It is guaranteed that the sum of n over all test cases does not exceed 2⋅105.
Output
For each test case, output the minimum possible size of the array after applying some sequence of operations to it.
Example Input
5
6
1 6 1 1 4 4
2
1 2
2
1 1
5
4 5 4 5 4
6
2 3 2 1 3 1
Output
2
1
题意:在数组中选择两个不同的数字,然后移除,直到不能选择,看看数组中剩下多少个数,数组可以为空。
1、只有一种数字,答案为该数字数量。
2、两种数字,答案为大的数量减去小的数量。
3、三种数字,假设数量从小到大排序 s1 s2 s3 ,可以知道当s1+s2<=s3, 答案为s3-(s1+s2)。
4、当 s1+s2>s3 ,如果(s1+s2+s3)%2 == 0,答案为0,
5、(s1+s2+s3)%2 == 1,答案为1。然后对于数字种数为3个以上的情况,其实都可以转化为3个的情况。
AC代码:
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<stdlib.h>
#include<queue>
#include<stack>
#include<algorithm>
using namespace std;
typedef long long ll;
const int maxn=2*1e5+10;
ll a[maxn];
int main()
{
ll t,n,i;
scanf("%d",&t);
while(t--)
{
scanf("%lld",&n);
for(i=0; i<n; i++)
scanf("%lld",&a[i]);
sort(a,a+n);
ll k=1,maxx=0;
for(i=1; i<n; i++)
{
if(a[i]==a[i-1])
k++;
else
{
maxx=max(k,maxx);
k=1;
}
}
maxx=max(k,maxx);//求最多元素的个数
k=maxx-(n-maxx);
if(k<0&&n%2==0)
k=0;
else if(k<0&&n%2!=0)
k=1;
printf("%lld\n",k);
}
return 0;
}