正经题解

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
int n;
string s;
vector<vector<int>> c;
ll ans;
vector<int> stk;
vector<ll> d, su;
void dfs(int u){
    int dep = d.size(), m = -1;
    if(s[u-1]=='(') stk.push_back(dep);
    else if(!stk.empty()){ m = stk.back(); stk.pop_back(); }
    ll x = 0;
    if(m != -1) x = 1 + (m>0 ? d[m-1] : 0);
    d.push_back(x);
    su.push_back((dep>0 ? su[dep-1] : 0) + x);
    ans ^= (ll)u * su[dep];
    for(int v : c[u]) dfs(v);
    d.pop_back(); su.pop_back();
    if(m != -1) stk.push_back(m);
    if(s[u-1]=='(') stk.pop_back();
}
int main(){
    cin>>n>>s;
    c.assign(n+1, {});
    for(int i=2,p;i<=n;i++){ cin>>p; c[p].push_back(i); }
    dfs(1);
    cout<<ans;
}