B. BerSU Ball

B. BerSU Ball

排序后考虑\(dp\),\(dp_{i,j}\)表示前\(i\)个男生和前\(j\)个女生能匹配的最大数.

\[\begin{aligned}

if(|a_i - b_j| \le 1) \ dp_{i,j} = dp_{i-1,j-1} + 1 \\ else \ \ \ \ \ \ \ \ dp_{i,j}=\max(dp_{i-1,j},dp_{i,j-1})

\end{aligned}
\]

#include <bits/stdc++.h>
#define debug(a) cout<<#a<<"="<<a<<'\n';

using namespace std;
using i64 = long long;

typedef pair<i64, i64> PII;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int n, m;
	cin >> n ;
	vector<int> a(n + 1);
	for (int i = 1; i <= n; i ++ )
		cin >> a[i];
	cin >> m;
	vector<int> b(m + 1);
	for (int j = 1; j <= m; j ++)
		cin >> b[j];

	sort(a.begin() + 1, a.end());
	sort(b.begin() + 1, b.end());
	vector dp(n + 1, vector<int>(m + 1));
	for (int i = 1; i <= n; i ++) {
		for (int j = 1; j <= m; j ++) {
			if (abs(a[i] - b[j]) <= 1)
				dp[i][j] = dp[i - 1][j - 1] + 1;
			else
				dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
		}
	}

	cout << dp[n][m] << '\n';

	return 0;
}