Why my this solution giving runtime error?

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

#define ll long long
#define int long long
#define all(v) v.begin(), v.end()
#define nl cout << "\n"
#define co(a) { cout << a << ' '; }
#define cou(a) { cout << a << "\n"; }
#define lcou(v) { for (auto& x : v) co(x); nl }
#define cy(x) { if(x) cou("YES") else cou("NO") }

const int M = 1e9 + 7;
const int N = 5010;

ll n, targ[N][N];
ll inf = 1e18;
vector<ll> e[N];
ll a[N], ans[N];

void dfs(ll x) {
    if (e[x].empty()) {
        for (int i = 1; i <= n; i++) {
            targ[x][i] = inf;
        }
        ans[x] = 0;
        return;
    }
    
    ll sums = 0;
    ans[x] = 0;
    for (auto j : e[x]) {
        dfs(j);
        ans[x] += ans[j];
        sums += a[j];
    }
    
    ll del = a[x] - sums;
    for (int i = 1; i <= n; i++) {
        if (del <= 0) break;
        for (auto j : e[x]) {
            if (del <= 0) break;
            if (targ[j][i] <= del) {
                ans[x] += i * targ[j][i];
                del -= targ[j][i];
                targ[j][i] = 0;
            } else {
                ans[x] += i * del;
                targ[j][i] -= del;
                del = 0;
            }
        }
    }
    
    if (del < 0) targ[x][1] = -del;
    for (int i = 2; i <= n; i++) {
        ll nsum = 0;
        for (auto j : e[x]) {
            if (targ[j][i - 1] == inf) {
                nsum = inf;
                break;
            }
            nsum += targ[j][i - 1];
        }
        targ[x][i] = nsum;
    }
}

void solve() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        e[i].clear();
    }
    
    for (int i = 1; i <= n; i++) {
        ans[i] = 0;
        for (int j = 1; j <= n; j++) {
            targ[i][j] = 0;
        }
    }
    
    for (int i = 2; i <= n; i++) {
        ll f;
        cin >> f;
        e[f].push_back(i);
    }
    
    dfs(1);
    cou(ans[1]);
}

signed main() {

    
    int TC;
    cin >> TC;
    while (TC--) {
        solve();
    }
    
    return TC;
}

Can someone explain this to me, last 5 minutes i tried to submit but it is giving Runtime error