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| #include <bits/stdc++.h>
#pragma optimization_level 3
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")
struct PairHash {
inline std::size_t operator()(const std::pair<int, int> &v) const { return v.first * 31 + v.second; }
};
#define M_PI 3.14159265358979323846
#define MAX_N 202020
#define INF 987654321
#define EPS 1e-9
#define ll long long
#define pll pair<ll, ll>
#define vpll vector<pll>
#define vall3 vector<array<ll,3>>
#define all3 array<ll,3>
#define all5 array<ll,5>
#define vall5 vector<all5>
#define vll vector<ll>
#define vi vector<int>
#define vs vector<string>
#define usll unordered_set<ll>
#define uspll unordered_set<pll, PairHash>
#define umll unordered_map<ll,ll>
#define vvs vector<vs>
#define vvll vector<vll>
#define all(a) begin(a), end(a)
#define rall(a) rbegin(a), rend(a)
ll __gcd(ll x, ll y) { return !y ? x : __gcd(y, x % y); }
using namespace std;
vll solve(vll& A, ll& k) {
usll us(all(A));
if(us.size() > k) return {};
vll B(all(us));
while(B.size() != k) B.push_back(1);
ll n = A.size(), m = B.size(), i = 0, j = 0;
vll res;
while(i < n) {
res.push_back(B[j]);
if(A[i] == B[j]) i++;
j = (j + 1) % m;
}
return res;
}
int main() {
ios_base::sync_with_stdio(0);
ios::sync_with_stdio(0);
cin.tie(0);
cout.precision(12);
ll tc = 1;
cin>>tc;
for (ll i = 1; i <= tc; i++) {
ll n, k;
cin>>n>>k;
vll A(n);
for(ll j = 0; j < n; j++) cin>>A[j];
auto res = solve(A, k);
if(res.empty()) cout<<"-1"<<endl;
else {
cout<<res.size()<<endl;
for(auto& r : res) cout<<r<<' ';cout<<endl;
}
}
return 0;
}
|
