CodeChef December Challenge 2017 Chef and Hamming Distance of arrays

https://www.codechef.com/DEC17/problems/CHEFHAM

#include<cstdio>
#include<cstring>
#include<iostream>
 
using namespace std;
 
#define N 100001
 
int a[N],b[N];
int sum[N],wh[N][2];
 
int num1[N],num2[N];
 
void read(int &x)
{
    x=0; char c=getchar();
    while(!isdigit(c)) c=getchar();
    while(isdigit(c)) { x=x*10+c-'0'; c=getchar(); }
}
 
int main()
{
    int T;
    read(T);
    int n;
    int tot1,tot2;
    while(T--)
    {
        memset(sum,0,sizeof(sum));
        memset(wh,0,sizeof(wh));
        read(n);
        for(int i=1;i<=n;++i)
        {
            read(a[i]);
            sum[a[i]]++;
            if(wh[a[i]][0]) wh[a[i]][1]=i;
            else wh[a[i]][0]=i;
        }
        tot1=tot2=0;
        for(int i=1;i<N;++i)
        {
            if(sum[i]&1) num1[++tot1]=i;
            else if(sum[i]) num2[++tot2]=i;
        }
        
        if(tot1==1 &&  tot2==1) 
        {
            cout<<n-1<<'
';
            b[wh[num1[1]][0]]=num1[1];
            b[wh[num2[1]][0]]=b[wh[num2[1]][1]]=num2[1]; 
            swap(b[wh[num1[1]][0]],b[wh[num2[1]][0]]);
        }
        else if((tot1==1 && !tot2) || (tot2==1 && !tot1)) 
        {
            cout<<0<<'
';
            for(int i=1;i<=n;++i) b[i]=a[i]; 
        } 
        else 
        {
            cout<<n<<'
';
            if(tot1==1)
            {
                for(int i=1;i<tot2;++i) b[wh[num2[i]][0]]=num2[i+1],b[wh[num2[i]][1]]=num2[i+1];
                b[wh[num2[tot2]][0]]=b[wh[num2[tot2]][1]]=num2[1];
                b[wh[num1[1]][0]]=num1[1];
                swap(b[wh[num2[1]][0]],b[wh[num1[1]][0]]);
            }
            else if(tot2==1)
            {
                for(int i=1;i<tot1;++i) b[wh[num1[i]][0]]=num1[i+1];
                b[wh[num1[tot1]][0]]=num1[1];
                b[wh[num2[1]][0]]=b[wh[num2[1]][1]]=num2[1]; 
                swap(b[wh[num2[1]][0]],b[wh[num1[1]][0]]);
                swap(b[wh[num2[1]][1]],b[wh[num1[2]][0]]);
            }
            else
            {
                for(int i=1;i<tot1;++i) b[wh[num1[i]][0]]=num1[i+1];
                b[wh[num1[tot1]][0]]=num1[1];
                for(int i=1;i<tot2;++i) b[wh[num2[i]][0]]=num2[i+1],b[wh[num2[i]][1]]=num2[i+1];
                b[wh[num2[tot2]][0]]=b[wh[num2[tot2]][1]]=num2[1];
            }
        }
        for(int i=1;i<=n;++i) cout<<b[i]<<' ';
        cout<<'
';
    }
} 

Read problems statements in Vietnamese

.

Chef likes to work with arrays a lot. Today he has an array A of length N consisting of positive integers. Chef's little brother likes to follow his elder brother, so he thought of creating an array B of length N. The little brother is too small to think of new numbers himself, so he decided to use all the elements of array A to create the array B. In other words, array B is obtained by shuffling the elements of array A.

The little brother doesn't want Chef to know that he has copied the elements of his array A. Therefore, he wants to create the array B in such a way that the Hamming distance between the two arrays A and B is maximized. The Hamming distance betweenA and B is the number of indices i (1 ≤ i ≤ N) such that A_i ≠ B_i.

The brother needs your help in finding any such array B. Can you please find one such array for him?

Note that it's guaranteed that no element in A appears more than twice, i.e. frequency of each element is at most 2.

Input

• The first line of the input contains a single integer T denoting the number of test cases. The description of T test cases follows.
• The first line of each test case contains an integer N denoting the length of the array A.
• The second line contains N space-separated integers A₁, A₂ ... A_N.

Output

• For each test case, print two lines.
• The first line should contain the maximum possible Hamming distance that array Bcan have from array A.
• The second line should contain N space-separated integers denoting the array B; the i-th integer should denote the value of B_i. Note that B should be an array obtained after shuffling the elements of A.

Constraints

• 1 ≤ T ≤ 10
• 1 ≤ N ≤ 10⁵
• 1 ≤ A_i ≤ 10⁵
• The frequency of each integer in the array A will be at most 2.

Subtasks

Subtask #1 (30 points): all elements in the array A are unique

Subtask #2 (30 points): 5 ≤ N ≤ 10⁵

Subtask #3 (40 points): original constraints

Example

Input

3
2
1 2
3
1 2 1
4
2 6 5 2

Output

2
2 1
2
2 1 1
4
6 2 2 5