这题只能分解轻重儿子吗，像下面这种暴力交换的一直过不去，是我有地方可以优化吗，求助

#include <bits/stdc++.h>
#define endl '\n'
using namespace std;
typedef long long ll;
const int N = 5e5 + 10;
map<int, int> mp[N];
vector<pair<int, int>> g[N];
int ans[N], dep[N], mask[N], id[N];
void solve() {
    int n;
    cin >> n;
    for (int i = 2; i <= n; i++) {
        int x;
        char c;
        cin >> x >> c;
        g[x].emplace_back(i, 1 << (c - 'a'));
    }
    for (int i = 1; i <= n; i++) {
        id[i] = i;
    }
    function<void(int)> dfs = [&](int u) {
        mp[u][mask[u]] = dep[u];
        for (auto [v, c] : g[u]) {
            dep[v] = dep[u] + 1;
            mask[v] = mask[u] ^ c;
            dfs(v);
            ans[u] = max(ans[u], ans[v]);
            if (mp[id[u]].size() < mp[id[v]].size()) {
                swap(id[u], id[v]);
            }
            int res = 0;
            for (auto &[k, v] : mp[id[v]]) {
                if (mp[id[u]].count(k)) {
                    res = max(res, v + mp[id[u]][k]);
                }
                for (int j = 0; j < 22; j++) {
                    if (mp[id[u]].count(k ^ (1 << j))) {
                        res = max(res, v + mp[id[u]][k ^ (1 << j)]);
                    }
                }
            }
            for (auto &[k, v] : mp[id[v]]) {
                mp[id[u]][k] = max(mp[id[u]][k], v);
            }
            ans[u] = max(ans[u], res - 2 * dep[u]);
        }
    };
    dfs(1);
    for (int i = 1; i <= n; i++) {
        cout << ans[i] << " ";
    }
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int T = 1;
    while (T--) {
        solve();
    }
    return 0;
}