1994.cpp

// Ivan Carvalho
// Solution to https://www.beecrowd.com.br/judge/problems/view/1994
#include <cstdio>
#include <vector>
#define MAXN 10010
using namespace std;
int processado[MAXN], n, anterior, maximo, aux;
vector<int> grafo[MAXN];
void dfs(int v, int percorrido) {
    processado[v] = 1;
    if (percorrido > maximo) {
        aux = v;
        maximo = percorrido;
    }
    for (int i = 0; i < grafo[v].size(); i++) {
        int u = grafo[v][i];
        if (!processado[u]) {
            dfs(u, percorrido + 1);
        }
    }
}
int main() {
    while (scanf("%d", &n) && n != -1) {
        maximo = 0;
        for (int i = 1; i <= n; i++) {
            grafo[i].clear();
            processado[i] = 0;
        }
        for (int i = 2; i <= n; i++) {
            scanf("%d", &anterior);
            grafo[anterior].push_back(i);
            grafo[i].push_back(anterior);
        }
        dfs(1, 0);
        for (int i = 1; i <= n; i++) processado[i] = 0;
        maximo = 0;
        dfs(aux, 0);
        printf("%d\n", (maximo + 1) / 2);
    }
    return 0;
}