Kodekode

# include <bits/stdc++.h>
# define sz(s) int(s.size())
# define IoS ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
  using namespace std;
  long long timber;
  long long arr[200200];
  int fir[100100], hrr[100100], tree[4004000];
  vector< int > vrr[100100], order, bur;
  void way(int v, int p = -1, int h = 0)
  {
      order.push_back(v);
      hrr[v] = h;
      if(fir[v] == -1) fir[v] = sz(order) - 1;
      for(int x : vrr[v]){
        if(x != p){
            way(x, v, h + 1);
            order.push_back(v);
        }
      }
  }
  void build_t(int v, int tl, int tr)
  {
      ///cout << " v = " << v << " tl = " << tl << " tr = " << tr << '\n';
      int a;
      ///cin >>a;
      if(tl == tr) tree[v] = order[tl];
      else {
        int tm = ((tl + tr) >> 1);
        build_t((v << 1), tl, tm);
        build_t((v << 1) + 1, tm + 1, tr);
        if(hrr[tree[(v << 1)]] < hrr[tree[(v << 1) + 1]]) tree[v] = tree[(v << 1)];
        else tree[v] = tree[(v << 1) + 1];
      }
  }
  int get_mn(int v, int tl, int tr, int le, int ri)
  {
      if((tr < le) || (ri < tl)) return 100000000;
      else if((le <= tl) && (tr <= ri)) return tree[v];
      else {
        int tm = ((tl + tr) >> 1), a, b;
        a = get_mn((v << 1), tl, tm, le, ri);
        b = get_mn((v << 1) + 1, tm + 1, tr, le, ri);
        if(a == 100000000) return b;
        else {
            if(b == 100000000) return a;
            else {
                if(hrr[a] < hrr[b]) return a;
                return b;
            }
        }
      }
  }
  int main()
  {
      long long n, m, p, K, v, s, x, y, z;
      cin >> n >> m;
      for(int i = 1; i < n; i++){
        cin >> p;
        fir[i] = fir[i - 1] = -1;
        vrr[i].push_back(p);
        vrr[p].push_back(i);
      }
      cin >> arr[1] >> arr[2] >> x >> y >> z;
      for(long long i = 3, M = 2 * m; i <= M; i++){
        arr[i] = ((arr[i - 2] * x) + (arr[i - 1] * y) + z) % n;
      }
      way(0);
      ///cout << " F 1 " << '\n';
      K = sz(order) - 1;
      ///cout << " F 2 " << '\n';
      build_t(1, 0, K);
      ///cout << " F 3" << '\n';
      v = get_mn(1, 0, K, min(fir[arr[1]], fir[arr[2]]), max(fir[arr[1]], fir[arr[2]]));
      ///cout << " v = " << v << '\n';
      s = v;
      for(int i = 2; i <= m; i++){
        long long a = (arr[(2 * i) - 1] + v) % n, b = arr[2 * i];
        if(fir[a] > fir[b]) swap(a, b);
        cout << " a = " << a << " b = " << b << '\n';
        v = get_mn(1, 0, K, fir[a], fir[b]);
        s += v;
      }
      cout << s;
      return 0;
  }
/**
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08.04.2017 ( ) - 0166
10.04.2017 ( ) - 0027
11.04.2017 ( ) - 0672
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13.04.2017 ( ) - 0602
17.04.2017 ( ) - 0570
18.04.2017 ( ) - 0310

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0174



*/