# include <iostream>
# include <vector>
using namespace std;
const int MAX=2e5+11;
int n,q,m;
int a[MAX];
bool used[MAX];
vector<int> v;
void read()
{
cin>>n>>q;
for(int i=1;i<=q;i++)
{
cin>>a[i];
used[a[i]]=1;
}
}
void print_moves()
{
cout<<0<<"\n";
/*
cout<<v.size()<<"\n";
for(int x: v) cout<<x<<" ";
cout<<"\n";
*/
}
void doit(int l, int r)
{
//cout<<l<<" "<<r<<"\n";
int sz=(r-l+1);
int cut=(l+r)/2;
while(sz>2)
{
sz-=2;
v.push_back(cut);
}
}
bool alone[MAX];
bool f=1;
vector<pair<int,int>> len;
void doit2(vector<pair<int, int>> curr)
{
vector<bool> rem((int)curr.size(),0);
for(int i=0;i<(int)curr.size()-1;i++)
{
//cout<<"->"<<curr[i].first<<" "<<curr[i].second<<"\n";
//if(i==0) cout<<"-->"<<curr[i+1].first<<" "<<curr[i+1].second<<"\n";
if(curr[i].second<0) {f=0;return ;}
if(rem[i]==1 and curr[i].second%2==0) continue;
if(curr[i].second%2==0)
{
rem[i]=1;
rem[i+1]=1;
curr[i].second-=2;
curr[i+1].second-=2;
}
else
{
rem[i]=1;
rem[i+1]=1;
curr[i].second--;
curr[i+1].second--;
}
if(curr[i].second<0) {f=0;return ;}
}
int sz=curr.size()-1;
if(curr[sz].second<0) {f=0;return ;}
if(rem[sz] and curr[sz].second%2==0) return ;
if(curr[sz].second%2==0)
{
if(curr[sz-1].second%2==0)
{
if(curr[sz-1].second>=2 and curr[sz].second>=2) return ;
else {f=0;return ;}
}
else {f=0;return ;}
}
else
{
if(curr[sz-1].second%2!=0)
{
if(curr[sz-1].second>=1 and curr[sz].second>=1) return ;
else {f=0;return ;}
}
else {f=0;return ;}
}
//cout<<"\n";
}
void solve()
{
if(n==q) {cout<<0<<"\n";return ;}
int start=-1;
for(int i=1;i<=n;i++)
{
if(used[i]==0)
{
if(start==-1) start=i;
}
else
{
if(start!=-1) len.push_back({start,i-1});
start=-1;
}
}
if(start!=-1) len.push_back({start,n});
int m=len.size();
vector<int> sz;
for(int i=0;i<m;i++)
{
//cout<<i<<":"<<len[i].first<<" "<<len[i].second<<"\n";
//doit(len[i].first,len[i].second);
//int p=(len[i].second-len[i].first+1)%2;
//if(p==0) p+=2;
sz.push_back(len[i].second-len[i].first+1);
//cout<<sz.back()<<"\n";
if(i>0 and len[i-1].second+2==len[i].first)
{
alone[i-1]=0;
alone[i]=0;
}
}
for(int i=0;i<m;i++) if(alone[i]) {cout<<-1<<"\n";return ;}
vector<pair<int, int>> curr;
for(int i=0;i<m;i++)
{
if(i>0 and len[i-1].second+2==len[i].first)
{
curr.push_back({i,sz[i]});
}
else
{
if((int)curr.size()>0) doit2(curr);
curr.clear();
curr.push_back({i,sz[i]});
}
}
if((int)curr.size()>0) doit2(curr);
if(f) print_moves();
else cout<<-1<<"\n";
}
void reset()
{
f=1;
v.clear();
len.clear();
for(int i=1;i<=n;i++) used[i]=0;
for(int i=0;i<=n;i++) alone[i]=1;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
int t;
cin>>t;
while(t--)
{
reset();
read();
solve();
}
return 0;
}
/**
3
5 1
3
7 3
1 5 7
7 3
1 2 7
*/
/**
1
5 1
3
*/
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
344 KB |
Output is partially correct |
2 |
Correct |
1 ms |
344 KB |
Output is partially correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
344 KB |
Output is partially correct |
2 |
Correct |
1 ms |
344 KB |
Output is partially correct |
3 |
Incorrect |
2 ms |
344 KB |
Output isn't correct |
4 |
Incorrect |
2 ms |
344 KB |
Output isn't correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
344 KB |
Output is partially correct |
2 |
Correct |
1 ms |
600 KB |
Output is partially correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
344 KB |
Output is partially correct |
2 |
Correct |
1 ms |
344 KB |
Output is partially correct |
3 |
Incorrect |
2 ms |
344 KB |
Output isn't correct |
4 |
Incorrect |
2 ms |
344 KB |
Output isn't correct |
5 |
Incorrect |
1 ms |
472 KB |
Output isn't correct |
6 |
Incorrect |
1 ms |
344 KB |
Output isn't correct |
7 |
Incorrect |
0 ms |
348 KB |
Output isn't correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
344 KB |
Output is partially correct |
2 |
Correct |
1 ms |
344 KB |
Output is partially correct |
3 |
Incorrect |
2 ms |
344 KB |
Output isn't correct |
4 |
Incorrect |
2 ms |
344 KB |
Output isn't correct |
5 |
Incorrect |
1 ms |
472 KB |
Output isn't correct |
6 |
Incorrect |
1 ms |
344 KB |
Output isn't correct |
7 |
Incorrect |
0 ms |
348 KB |
Output isn't correct |
8 |
Incorrect |
6 ms |
860 KB |
Output isn't correct |
9 |
Incorrect |
4 ms |
992 KB |
Output isn't correct |
10 |
Incorrect |
4 ms |
1116 KB |
Output isn't correct |
11 |
Incorrect |
4 ms |
1460 KB |
Output isn't correct |