题解(老师的)

#include<bits/stdc++.h>
using namespace std;
const int N=200010;
const int mod =1e9+7;
int dp[2][N];
string s[2];
int t,m;
void solve(){
    cin>>m;
    cin>>s[0]>>s[1];
    int cnt=count(s[0].begin(),s[0].end(),'B')+count(s[1].begin(),s[1].end(),'B');
    for (int i = 0; i < m; i++){
		if (s[0][i] == 'B'){
            dp[0][i] = 1;
        }else{
            dp[0][i] = 0;
        }
		if (s[1][i] == 'B'){
            dp[1][i] = 1;
        }else{
            dp[1][i] = 0;
        }
	}
    for (int i = 0; i < m; i++){
		if (s[0][i] == 'B' && i >= 1){
            dp[0][i] += dp[0][i - 1];
        }
		if (s[1][i] == 'B' && i >= 1){
            dp[1][i] += dp[1][i - 1];
        }

		if (s[0][i] == 'B' && s[1][i] == 'B'){
			int tmp = dp[0][i];
			dp[0][i] = max(dp[0][i], dp[1][i] + 1);
			dp[1][i] = max(dp[1][i], tmp + 1);
		}
	}
    if (dp[0][m - 1] == cnt || dp[1][m - 1] == cnt){
        cout << "YES"<<endl;
    }else{
        cout << "NO"<<endl;
    }
}
int main(){
	cin >> t;
	while(t--){
        solve();
    }
	return 0;
}