小码君的路

#include <bits/stdc++.h>

using namespace std;

string s, t;
int q, m;
int dp[2][200005]; // 走到(i,j)会走多少个b

int main()
{
	cin >> q;
	while (q--)
	{
		cin >> m >> s >> t;
		int cnt = 0;
		for (int i = 0; i < m; i++)
			cnt += s[i] == 'B';
		for (int i = 0; i < m; i++)
			cnt += t[i] == 'B';

		for (int i = 0; i < m; i++) // 初始化
		{
			if (s[i] == 'B')
				dp[0][i] = 1;
			else
				dp[0][i] = 0;
			if (t[i] == 'B')
				dp[1][i] = 1;
			else
				dp[1][i] = 0;
		}

		for (int i = 0; i < m; i++)
		{
			if (s[i] == 'B' && i >= 1) // 从左边转移过来
				dp[0][i] += dp[0][i - 1];
			if (t[i] == 'B' && i >= 1)
				dp[1][i] += dp[1][i - 1];

			if (s[i] == 'B' && t[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\n";
		else
			cout << "NO\n";
	}
	return 0;
}