Problem p00777 (C++) — buggy submission, verdict: Time Limit Exceeded

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

#define fi first
#define se second
#define repl(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define repr(i, n) for (int i = (int)(n - 1); i >= 0; i--)
#define rep(i, n) repl(i, 0, n)
#define each(itr, v) for (auto itr : v)
#define pb(s) push_back(s)
#define all(x) (x).begin(), (x).end()
#define dbg(x) cout << #x " = " << x << endl
#define print(x) cout << x << endl
#define maxch(x, y) x = max(x, y)
#define minch(x, y) x = min(x, y)
#define uni(x) x.erase(unique(all(x)), x.end())
#define exist(x, y) (find(all(x), y) != x.end())
#define bcnt(x) bitset<32>(x).count()

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
typedef pair<P, int> PPI;
typedef pair<int, P> PIP;
typedef pair<ll, ll> PL;
typedef pair<P, ll> PPL;

#define INF INT_MAX / 3
#define MAX_N 1000000001

int n;
int d[800][800];
bool visited[800];
int maxi, u;
set<int> st;

void dfs(int v, int c) {
  visited[v] = true;

  bool end = true;
  rep(i, n) {
    if (d[v][i] < INF && !visited[i] && !st.count(i)) {
      end = false;
      dfs(i, c + d[v][i]);
    }
  }

  if (end) {
    if (maxi <= c) {
      maxi = c;
      u = v;
    }
  }
}

int main() {
  cin.sync_with_stdio(false);
  while (cin >> n, n) {
    rep(i, n) rep(j, n) d[i][j] = INF;
    st.clear();

    vector<int> p(n);
    int sum = 0;
    repl(i, 1, n) cin >> p[i], p[i]--;
    repl(i, 1, n) {
      int tmp;
      cin >> tmp;
      d[i][p[i]] = d[p[i]][i] = tmp;
      sum += tmp;
    }

    int e = 0, tmp = -1;
    rep(i, n) {
      int cnt = 0, len = 0;
      rep(j, n) if (d[i][j] < INF) cnt++, len = d[i][j];
      if (cnt == 1)
        st.insert(i), e += len;
      else
        tmp = i;
    }

    if (tmp >= 0) {
      memset(visited, 0, sizeof(visited)), maxi = 0;
      dfs(tmp, 0), tmp = u;
      memset(visited, 0, sizeof(visited)), maxi = 0;
      dfs(tmp, 0);
    } else
      maxi = 0;

    int ans = maxi * 2 + e + (sum - maxi - e) * 3;
    cout << ans << endl;
  }

  return 0;
}

Error: TLE

Fixed submission:

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

#define fi first
#define se second
#define repl(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define repr(i, n) for (int i = (int)(n - 1); i >= 0; i--)
#define rep(i, n) repl(i, 0, n)
#define each(itr, v) for (auto itr : v)
#define pb(s) push_back(s)
#define all(x) (x).begin(), (x).end()
#define dbg(x) cout << #x " = " << x << endl
#define print(x) cout << x << endl
#define maxch(x, y) x = max(x, y)
#define minch(x, y) x = min(x, y)
#define uni(x) x.erase(unique(all(x)), x.end())
#define exist(x, y) (find(all(x), y) != x.end())
#define bcnt(x) bitset<32>(x).count()

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
typedef pair<P, int> PPI;
typedef pair<int, P> PIP;
typedef pair<ll, ll> PL;
typedef pair<P, ll> PPL;

#define INF INT_MAX / 3
#define MAX_N 1000000001

int n;
int d[800][800];
// bool visited[800];
// int maxi, u;
// set<P> st;

/*void dfs(int v, int c) {
    visited[v] = true;

    bool end = true;
    rep(i, n) {
        if (d[v][i] < INF && !visited[i]) {
            end = false;
            dfs(i, c + d[v][i]);
        }
    }

    if (end) {
        if (maxi < c) {
            maxi = c;
            u = v;
        }
        rep(i, n) if (d[v][i] < INF) st.insert(P(v, d[v][i]));
    }
}*/

int main() {
  cin.sync_with_stdio(false);
  while (cin >> n, n) {
    rep(i, n) rep(j, n) d[i][j] = (i == j) ? 0 : INF;

    vector<int> p(n);
    int sum = 0;
    repl(i, 1, n) cin >> p[i], p[i]--;
    repl(i, 1, n) {
      int tmp;
      cin >> tmp;
      d[i][p[i]] = d[p[i]][i] = tmp;
      sum += tmp;
    }

    set<int> st;
    int e = 0;
    rep(i, n) {
      int cnt = 0, len = 0;
      rep(j, n) if (i != j && d[i][j] < INF) cnt++, len = d[i][j];
      if (cnt == 1)
        st.insert(i), e += len;
    }

    rep(i, n) rep(j, n) rep(k, n) minch(d[j][k], d[j][i] + d[i][k]);
    int maxi = 0;
    rep(i, n) rep(j, n) {
      if (st.count(i))
        break;
      if (st.count(j))
        continue;
      maxch(maxi, d[i][j]);
    }

    int ans = maxi * 2 + e + (sum - maxi - e) * 3;
    cout << ans << endl;
  }

  return 0;
}