CF455C Civilization

Toot toot


water problem together in some valley and malicious score.


Merge is nothing more than the midpoint of the diameter of two trees even one, remember the original two trees of a diameter of \ (D_1, d_2 \) , then the diameter of the new tree is \ (max (d_1, d_2, \ lceil \ frac D_1} {2} {\ rceil + \ lceil \ FRAC D_2} {2} {\ + rceil. 1) \) , and a check and set, to update.

#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<cstdlib>
#include<cctype>
#include<vector>
#include<stack>
#include<queue>
#include<assert.h>
using namespace std;
#define enter puts("") 
#define space putchar(' ')
#define Mem(a, x) memset(a, x, sizeof(a))
#define In inline
typedef long long ll;
typedef double db;
const int INF = 0x3f3f3f3f;
const db eps = 1e-8;
const int maxn = 3e5 + 5;
In ll read()
{
  ll ans = 0;
  char ch = getchar(), last = ' ';
  while(!isdigit(ch)) last = ch, ch = getchar();
  while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();
  if(last == '-') ans = -ans;
  return ans;
}
In void write(ll x)
{
  if(x < 0) x = -x, putchar('-');
  if(x >= 10) write(x / 10);
  putchar(x % 10 + '0');
}
In void MYFILE()
{
#ifndef mrclr
  freopen(".in", "r", stdin);
  freopen(".out", "w", stdout);
#endif
}

int n, m, Q;
struct Edge
{
  int nxt, to;
}e[maxn << 1];
int head[maxn], ecnt = -1;
In void addEdge(int x, int y)
{
  e[++ecnt] = (Edge){head[x], y};
  head[x] = ecnt;
}

int p[maxn];
In int Find(int x) {return x == p[x] ? x : p[x] = Find(p[x]);}

int Max[maxn], dia[maxn];
In void dfs(int now, int _f, int id)
{
  p[now] = id;
  int Max1 = 0, Max2 = 0;
  for(int i = head[now], v; ~i; i = e[i].nxt)
    {
      if((v = e[i].to) == _f) continue;
      dfs(v, now, id);
      if(Max[v] + 1 > Max1) Max2 = Max1, Max1 = Max[v] + 1;
      else if(Max[v] + 1 > Max2) Max2 = Max[v] + 1;
    }
  Max[now] = Max1;
  dia[id] = max(dia[id], Max1 + Max2);
}

int main()
{
  //MYFILE();
  Mem(head, -1);
  n = read(), m = read(), Q = read();
  for(int i = 1; i <= m; ++i)
    {
      int x = read(), y = read();
      addEdge(x, y), addEdge(y, x);
    }
  for(int i = 1; i <= n; ++i) if(!p[i]) dfs(i, 0, i);
  for(int i = 1; i <= Q; ++i)
    {
      int op = read(), x = read();
      if(op == 1) write(dia[Find(x)]), enter;
      else
    {
      int y = read();
      int px = Find(x), py = Find(y);
      if(px == py) continue;
      p[px] = py;
      dia[py] = max(max(dia[px], dia[py]), (dia[px] + 1) / 2 + (dia[py] + 1) / 2 + 1);
    }
    }
  return 0;
}