1821D - Black Cells - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;
const int N=200200;
int n,k,sum,sun,minv,t,l[N],r[N];
int main(){
	cin>>t;
	while(t--){
		cin>>n>>k;
		minv=2e9,sun=sum=0;
		for(int i=1;i<=n;i++) cin>>l[i];
		for(int i=1;i<=n;i++){
			cin>>r[i];
			sun+=l[i]==r[i];
			sum+=r[i]-l[i]+1;
			if(sum>=k)
				minv=min(minv,r[i]-(sum-k)+(i<<1)-min(sun,sum-k));
		}
		if(minv==(2e9)) cout<<"-1"<<endl;
		else cout<<minv<<endl;
	}
}