题目

代码

#include<bits/stdc++.h>
using namespace std;

const int N = 2e5+10;

int a[N], b[N];
int ans;
vector<int> Ga[N], Gb[N];

void dfs(int ap, int af, int bp, int bf, int dep)
{
    ans = max(ans, dep);

    map<int, int> bk;

    for(auto ason : Ga[ap])
    if(ason != af) bk[a[ason]] = ason;

    for(auto bson : Gb[bp])
    if(bson != bf)
    if(bk.count(b[bson]))
    {
        dfs(bk[b[bson]], ap, bson, bp, dep+1);
    }
}
int main()
{
    int n, m;
    cin >> n >> m;

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

    int u, v;
    for(int i = 1; i < n; i++)
    {
        cin >> u >> v;
        Ga[u].push_back(v);
        Ga[v].push_back(u);
    }
    for(int i = 1; i < m; i++)
    {
        cin >> u >> v;
        Gb[u].push_back(v);
        Gb[v].push_back(u);
    }

    if(a[1] != b[1])
    {
        cout << 0;
        return 0;
    }

    dfs(1,0,1,0,1);
    cout << ans;

    return 0;
}