WA 代码：

#include<bits/stdc++.h>
using namespace std;
char a[2000005];
void solve()
{
	int n,m,ans=0,mx=0,sum=0,c1=0;
	char j; 
	cin>>n>>m;
	for(int i=0;i<n;i++)cin>>a[i];
	int last=0;
	for(int i=0;i<n;i++)
	{
		cin>>j;
		if(j=='1'&&a[i]=='1')sum+=2,last=0;
		else if(j=='0'&&a[i]=='0')sum-=1;
		else 
		{
			if(j=='0')
			{
				if(last!=2)last=1,sum+=1,c1++;
				else last=0;
			}
			else
			{
				if(last!=1)last=2,sum+=1,c1++;
				else last=0;
			} 
		}
		mx=max(mx,sum-min(m*2,c1));
		if(sum-min(m*2,c1)<0)sum=0,ans=max(ans,mx),mx=0,c1=0,last=0;
	}
	ans=max(ans,mx);
	cout<<ans<<endl;
}
int main() 
{
	//freopen("summer3.in","r",stdin);
	int n,_;
	cin>>_>>n;
	while(n--)
	{
		solve();
	}
    return 0;
}