CF-456E (simple tree diameter + disjoint-set)

Meaning of the questions: http://codeforces.com/problemset/problem/456/E

Ideas:

Disjoint-set is to pit, starting a path compression.

  1 #define IOS ios_base::sync_with_stdio(0); cin.tie(0);
  2 #include <cstdio>//sprintf islower isupper
  3 #include <cstdlib>//malloc  exit strcat itoa system("cls")
  4 #include <iostream>//pair
  5 #include <fstream>//freopen("C:\\Users\\13606\\Desktop\\Input.txt","r",stdin);
  6 #include <bitset>
  7 //#include <map>
  8 //#include<unordered_map>
  9 #include <vector>
 10 #include <stack>
 11 #include <set>
 12 #include <string.h>//strstr substr strcat
 13 #include <string>
 14 #include <time.h>// srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9;
 15 #include <cmath>
 16 #include <deque>
 17 #include <queue>//priority_queue<int, vector<int>, greater<int> > q;//less
 18 #include <vector>//emplace_back
 19 //#include <math.h>
 20 #include <cassert>
 21 #include <iomanip>
 22 //#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor
 23 #include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare)
 24 using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation
 25 //******************
 26 clock_t __START,__END;
 27 double __TOTALTIME;
 28 void _MS(){__START=clock();}
 29 void _ME(){__END=clock();__TOTALTIME=(double)(__END-__START)/CLOCKS_PER_SEC;cout<<"Time: "<<__TOTALTIME<<" s"<<endl;}
 30 //***********************
 31 #define rint register int
 32 #define fo(a,b,c) for(rint a=b;a<=c;++a)
 33 #define fr(a,b,c) for(rint a=b;a>=c;--a)
 34 #define mem(a,b) memset(a,b,sizeof(a))
 35 #define pr printf
 36 #define sc scanf
 37 #define ls rt<<1
 38 #define rs rt<<1|1
 39 typedef pair<int,int> PII;
 40 typedef vector<int> VI;
 41 typedef unsigned long long ull;
 42 typedef long long ll;
 43 typedef double db;
 44 const db E=2.718281828;
 45 const db PI=acos(-1.0);
 46 const ll INF=(1LL<<60);
 47 const int inf=(1<<30);
 48  const DB the ESP = 1E9 ;
 49  const  int MOD = ( int ) 1E9 + . 7 ;
 50  const  int N = ( int ) 1e6 + 10 ;
 51 is  
52 is  int FA [N];
 53 is  int Find ( int XA) {
 54 is      int XB = XA;   // initial value assigned to B 
55      the while (XA =! FA [XA]) {
 56 is          XA = FA [XA];   // find a ancestor node 
57 is      }
 58      the while(! XB = XA) {   // until A == b 
59          int TEMP = FA [XB]; // provided as intermediate variable b is a parent node 
60          FA [XB] = XA; // directly from the father b ancestor node is a node 
61 is          XB = TEMP;   // b = b parent node 
62 is      }
 63 is      return XA;
 64  }
 65  int len [N], Lent [N];
 66  BOOL VIS [N];
 67  
68  struct EDGE
 69  {
 70      int to, Next;
 71 is  } Edge [N];
 72  int Tot;
 73 is  int head[N];
 74 void Init(int n)
 75 {
 76     Tot=0;
 77     for(int i=0;i<=n;++i)
 78         head[i]=0;
 79 }
 80 void add(int from,int to)
 81 {
 82     ++Tot;
 83     edge[Tot].to=to;
 84     edge[Tot].next=head[from];
 85     head[from]=Tot;
 86 }//for(int i=head[x];i;i=edge[i].next)
 87 int TempNode,tot,TempC;
 88 void dfs(int u,int fu,int c,int nn)
 89 {
 90     fa[u]=nn;
 91     for(int i=head[u];i;i=edge[i].next)
 92     {
 93         int to=edge[i].to;
 94         if(to!=fu)
 95             dfs(to,u,c+1,nn);
 96     }
 97     if(c>TempC)
 98         TempC=c,TempNode=u;
 99 }
100 
101 int main()
102 {
103     int n,m,q;
104     sc("%d%d%d",&n,&m,&q);
105     for(int i=1;i<=n;++i)fa[i]=i;
106     for(int i=1;i<=m;++i)
107     {
108         int u,v;
109         sc("%d%d",&u,&v);
110         add(u,v);
111         add(v,u);
112     }
113     for(int i=1;i<=n;++i)
114     {
115         if(fa[i]!=i)continue;
116         TempNode=TempC=tot=0;
117         dfs(i,-1,1,i);
118         TempC=0;
119         dfs(TempNode,-1,1,TempNode);
120         len[TempNode]=TempC-1;
121     }
122     for(int i=1;i<=q;++i)
123     {
124         int op,x,y;
125         sc("%d",&op);
126         if(op==1)
127         {
128             sc("%d",&x);
129             pr("%d\n",len[find(x)]);
130         }
131         else
132         {
133             sc("%d%d",&x,&y);
134             int fx=find(x);
135             int fy=find(y);
136         //    if(fx>fy)swap(fx,fy);
137             if(fx==fy)continue;
138             len[fx]=max(max(len[fx],len[fy]),(len[fx]+1)/2+(len[fy]+1)/2+1);
139             fa[fy]=fx;
140         }
141     }
142     return 0;
143 }
144 
145 /**************************************************************************************/