Submission #467631

#	Time	Username	Problem	Language	Result	Execution time	Memory
467631		ivan_tudor	Dynamic Diameter (CEOI19_diameter)	C++14	0 / 100	5098 ms	7500 KiB

diameter

#include<bits/stdc++.h>
using namespace std;
// consideram initial ca toate distantele sunt 0 si apoi updatam cu costul muchiilor
const int N = 100005;
const int LOGN = 18;

// aint
long long aint[N * LOGN * 4 + 5];
long long lazy[N * LOGN * 4 + 5];
void propag(int nod, int l, int r){
  aint[nod] += 1LL * lazy[nod];
  if(l != r){
    lazy[2*nod] += lazy[nod];
    lazy[2*nod + 1] += lazy[nod];
  }
  lazy[nod] = 0;
}
void update(int nod, int l, int r, int ul, int ur, long long val){
  propag(nod, l, r);
  if(ur < l || r < ul)
    return;
  if(ul <= l && r <= ur){
    lazy[nod] += val;
    propag(nod, l, r);
    return;
  }
  int mid = (l + r)/2;
  update(2*nod, l, mid, ul, ur, val);
  update(2*nod + 1, mid + 1, r, ul, ur, val);
  aint[nod] = max(aint[2*nod], aint[2*nod + 1]);
}
long long query(int nod, int l, int r, int ql, int qr){
  propag(nod, l, r);
  if(r < ql || qr < l)
    return 0;
  if(ql <= l && r <= qr)
    return aint[nod];
  int mid = (l + r)/2;
  long long ls = query(2*nod, l, mid, ql, qr);
  long long rs = query(2*nod + 1, mid + 1, r, ql, qr);
  return max(ls, rs);
}
vector<int> gr[N];
int croot[LOGN][N];
int fson[LOGN][N];
int in[LOGN][N];
int out[LOGN][N];

bool wasC[N];
int sz[N];
void dfs_sz(int nod, int dad){
  sz[nod] = 1;
  for(auto x:gr[nod]){
    if(x!= dad && wasC[x] == false){
      dfs_sz(x, nod);
      sz[nod] += sz[x];
    }
  }
}
int find_centro(int nod, int dad, int bound){
  for(auto x:gr[nod]){
    if(wasC[x] == false && x!= dad && sz[x] > bound)
      return find_centro(x, nod, bound);
  }
  return nod;
}
void dfs_from_centro(int nod, int dad, int cnumber, int &id, int centro, int fs){
  if(dad == centro)
    fs = nod;
  croot[cnumber][nod] = centro;
  fson[cnumber][nod] = fs;
  in[cnumber][nod] = ++id;
  for(auto x:gr[nod]){
    if(x != dad && wasC[x] == false){
      dfs_from_centro(x, nod, cnumber, id, centro, fs);
    }
  }
  out[cnumber][nod] = id;
}
multiset<long long> best[N];
multiset<long long> bsum;
void centro_dec(int nod, int number, int &id){
  dfs_sz(nod, 0);
  int sze = sz[nod];
  int centro = find_centro(nod, 0, sze / 2);
  dfs_from_centro(centro, 0, number, id, centro, centro);
  for(auto x:gr[centro]){
    if(wasC[x] == false){
      best[centro].insert(0);
    }
  }
  bsum.insert(0);
  wasC[centro] = true;
  for(auto x:gr[centro]){
    if(wasC[x] == false)
      centro_dec(x, number + 1, id);
  }

}
int L, R;
long long sumbig2(multiset<long long> &s){
  long long sum =0;
  int cnt = 0;
  for(auto itr = s.rbegin(); itr != s.rend() && cnt < 2; itr++, cnt++){
    sum += (*itr);
  }
  return sum;
}
bool isdad(int number, int dad, int son){
  if(in[number][dad] <= in[number][son] && out[number][son] <= out[number][dad])
    return true;
  return false;
}
void update_edge(int nod, int onod, long long change){
  int number = 0;
  for(; number < LOGN; number++){
    if(croot[number][nod] == nod)
      break;
  }
  if(isdad(number, nod, onod) == false)
    number--;
  for(; number >= 0; number--){
    if(isdad(number, nod, onod) == true)
      swap(nod, onod);

    int centro = croot[number][nod];
    int fs = fson[number][nod];

    long long o_sum = sumbig2(best[centro]);
    bsum.erase(bsum.find(o_sum));

    long long old_big = query(1, L, R, in[number][fs], out[number][fs]);
    best[centro].erase(best[centro].find(old_big));

    update(1, L, R, in[number][nod], out[number][nod], change);

    long long new_big = query(1, L, R, in[number][fs], out[number][fs]);
    best[centro].insert(new_big);

    long long nsum = sumbig2(best[centro]);
    bsum.insert(nsum);
  }

}
struct edges{
  int x, y;
  long long c;
};
int main()
{
  freopen(".in","r",stdin);
  ios::sync_with_stdio(false);
  cin.tie(0),cout.tie(0);
  int n, q;
  long long w;
  cin>>n>>q>>w;
  vector<edges> es;
  for(int i = 0; i < n - 1; i++){
    int x, y, c;
    cin>>x>>y>>c;
    es.push_back({x, y, c});
    gr[x].push_back(y);
    gr[y].push_back(x);
  }
  centro_dec(1, 0, R);
  L = 1;
  for(int i = 0; i < n - 1; i++){
    update_edge(es[i].x, es[i].y, es[i].c);
  }
  cerr<<(*bsum.rbegin())<<"\n      ==================== \n";
  long long last = 0;
  for(int i = 1; i<=q; i++){
    long long d, e;
    cin>>d>>e;
    d = (last + d)%(n - 1);
    e = (last + e)% w;
    long long df = e - es[d].c;
    update_edge(es[d].x, es[d].y, df);
    es[d].c = e;
    last = (*bsum.rbegin());
    cout<<last<<"\n";
  }
  return 0;
}

Compilation message (stderr)

diameter.cpp: In function 'int main()':
diameter.cpp:151:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  151 |   freopen(".in","r",stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 13
• Subtask 3: 0 / 7
• Subtask 4: 0 / 18
• Subtask 5: 0 / 24
• Subtask 6: 0 / 27