随便秒杀的小题

#include <bits/stdc++.h>
#define endl '\n'
using namespace std;
const int N=1e5+5,INF=0x3f3f3f3f,MOD=1e9+7;
const int dx[]={1,-1,0,0},dy[]={0,0,1,-1};
typedef long long LL;
string a,b;
int lena,lenb;
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);cout.tie(nullptr);
	cin>>lena>>a>>lenb>>b;
	a = " "+a,b = " "+b;
	vector<vector<int>>dp(lena+1,vector<int>(lenb+1));
	for(int i=1;i<=lena;i++){
		for(int j=1;j<=lenb;j++){
			dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
			if(a[i]==b[j])dp[i][j] = max(dp[i-1][j-1]+1,dp[i][j]);	
		}
	}
	cout<<dp[lena][lenb]<<endl;
	return 0;
}