Codeforces Round #768 (Div. 2) C D

#include<bits/stdc++.h>
using namespace std;
int t,n,k;

int main(){
	cin>>t;
	while(t--){
		cin>>n>>k;
		if(n==4&&k==3){
			puts("-1");
			continue;
		}
		if(k==0){
			for(int i=0;i<n/2;i++){
				cout<<i<<" "<<n-1-i<<endl;
			}
			continue;
		}
		if(n!=k+1){
			cout<<n-1<<" "<<k<<endl;
			cout<<0<<" "<<n-1-k<<endl;
			for(int i=1;i<n/2;i++){
				if(i==k||n-1-i==k) continue;
				cout<<i<<" "<<n-1-i<<endl;
			}
		}
		else{
			cout<<n-1<<" "<<n-2<<endl;
			cout<<n-3<<" "<<1<<endl;
			cout<<2<<" "<<0<<endl;
			for(int i=3;i<n/2;i++){
				cout<<i<<" "<<n-1-i<<endl;
			}
		}
	}	
	return 0;
} 

#include<bits/stdc++.h>
using namespace std;
int t,n,k;
int a[200005];
int cnt[200005],pre[200005];

int main(){
	scanf("%d",&t);
	while(t--){
		scanf("%d%d",&n,&k);
		int num=(n+k+1)/2;
		for(int i=1;i<=n;i++) cnt[i]=0;
		for(int i=1;i<=n;i++){
			scanf("%d",&a[i]);
			cnt[a[i]]++;
		}
		pre[0]=0;
		for(int i=1;i<=n;i++){
			pre[i]=pre[i-1]+cnt[i];
		}
		
		int l=1,len=1e9,x,y;
		for(int r=1;r<=n;r++){
			while(pre[r]-pre[l-1]>=num){
				if(r-l+1<len){
					len=r-l+1;
					x=l;y=r;
				}
				l++;
			}
		}
		cout<<x<<" "<<y<<endl;
		
		if(k==1){
			printf("%d %d\n",1,n);
			continue;
		}
		int last=1,cnt=0,cnt1=0;
		int kk=0;
		for(int i=1;i<=n;i++){
			cnt++;
			if(a[i]>=x&&a[i]<=y) cnt1++;
			if(2*cnt1>cnt){
				cout<<last<<" "<<i<<endl;
				cnt1=0;cnt=0;
				last=i+1;
				kk++;
				if(kk==k-1){
					cout<<i+1<<" "<<n<<endl;
					break;
				}
			}
		}
		
	}	
	return 0;
}