Submission #867006

#	Time	Username	Problem	Language	Result	Execution time	Memory
867006		NeroZein	Dynamic Diameter (CEOI19_diameter)	C++17	100 / 100	402 ms	48940 KiB

diameter

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

#ifdef Nero
#include "Deb.h"
#else
#define deb(...)
#endif

const int N = 3e5 + 5;

int n; 
long long dis[N];
long long weight[N]; 
int cnt, in[N], out[N]; 
vector<pair<int, int>> g[N]; 

struct node {
  long long mx = 0, mn = 0, mxmn = 0, mnmx = 0, ans = 0, lazy = 0;
}seg[N * 4];

node merge(node& lx, node& rx) {
  node ret;
  ret.mx = max(lx.mx, rx.mx);
  ret.mn = min(lx.mn, rx.mn);
  ret.mxmn = max({lx.mxmn, rx.mxmn, lx.mx - 2LL * rx.mn});
  ret.mnmx = max({lx.mnmx, rx.mnmx, - 2LL * lx.mn + rx.mx}); 
  ret.ans = max({lx.ans, rx.ans, lx.mx + rx.mnmx, lx.mxmn + rx.mx});
  return ret;
}

void push(int nd, int l, int r) {
  if (!seg[nd].lazy) {
    return;
  }
  seg[nd].mx += seg[nd].lazy;
  seg[nd].mn += seg[nd].lazy;
  seg[nd].mxmn -= seg[nd].lazy;
  seg[nd].mnmx -= seg[nd].lazy; 
  if (l != r) {
    int mid = (l + r) / 2;
    int rs = nd + ((mid - l + 1) * 2);
    seg[nd + 1].lazy += seg[nd].lazy;
    seg[rs].lazy += seg[nd].lazy; 
  }
  seg[nd].lazy = 0;
}

void upd(int nd, int l, int r, int s, int e, long long v) {
  push(nd, l, r); 
  if (l >= s && r <= e) {    
    seg[nd].lazy = v;
    push(nd, l, r);
    return;
  }
  int mid = (l + r) / 2;
  int rs = nd + ((mid - l + 1) * 2);
  if (mid >= e) {
    upd(nd + 1, l, mid, s, e, v);
    push(rs, mid + 1, r); 
  } else {
    if (mid < s) {
      push(nd + 1, l, mid);
      upd(rs, mid + 1, r, s, e, v); 
    } else {
      upd(nd + 1, l, mid, s, e, v);
      upd(rs, mid + 1, r, s, e, v); 
    }
  }
  seg[nd] = merge(seg[nd + 1], seg[rs]); 
}

void dfs(int v, int pe) {
  cnt++; 
  for (auto [u, i] : g[v]) {
    if (i == pe) {
      continue;
    }
    dis[u] = dis[v] + weight[i]; 
    in[i] = cnt; 
    dfs(u, i); 
    out[i] = cnt - 1;
    upd(0, 0, 2 * n - 2, in[i], out[i], weight[i]); 
    cnt++; 
  }
}

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int q;
  long long lim;
  cin >> n >> q >> lim;
  for(int i = 0; i < n - 1; ++i) {
    int u, v;
    long long w;
    cin >> u >> v >> w;
    weight[i] = w; 
    g[u].emplace_back(v, i);
    g[v].emplace_back(u, i); 
  }
  dfs(1, n); 
  long long last = 0;
  while (q--) {
    long long d, c;
    cin >> d >> c;
    d = (d + last) % (n - 1);
    c = (c + last) % lim;
    upd(0, 0, 2 * n - 2, in[d], out[d], -weight[d]);
    weight[d] = c; 
    upd(0, 0, 2 * n - 2, in[d], out[d], +weight[d]);
    last = max(seg[0].mx, seg[0].ans);
    cout << last << '\n';  
  } 
  return 0;
}

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