ural 1272. Non-Yekaterinburg Subway

  1 /**
  2 Create By yzx - stupidboy
  3 */
  4 #include <cstdio>
  5 #include <cstring>
  6 #include <cstdlib>
  7 #include <cmath>
  8 #include <deque>
  9 #include <vector>
 10 #include <queue>
 11 #include <iostream>
 12 #include <algorithm>
 13 #include <map>
 14 #include <set>
 15 #include <ctime>
 16 #include <iomanip>
 17 using namespace std;
 18 typedef long long LL;
 19 typedef double DB;
 20 #define For(i, s, t) for(int i = (s); i <= (t); i++)
 21 #define Ford(i, s, t) for(int i = (s); i >= (t); i--)
 22 #define Rep(i, t) for(int i = (0); i < (t); i++)
 23 #define Repn(i, t) for(int i = ((t)-1); i >= (0); i--)
 24 #define rep(i, x, t) for(int i = (x); i < (t); i++)
 25 #define MIT (2147483647)
 26 #define INF (1000000001)
 27 #define MLL (1000000000000000001LL)
 28 #define sz(x) ((int) (x).size())
 29 #define clr(x, y) memset(x, y, sizeof(x))
 30 #define puf push_front
 31 #define pub push_back
 32 #define pof pop_front
 33 #define pob pop_back
 34 #define ft first
 35 #define sd second
 36 #define mk make_pair
 37 inline void SetIO(string Name)
 38 {
 39     string Input = Name+".in",
 40     Output = Name+".out";
 41     freopen(Input.c_str(), "r", stdin),
 42     freopen(Output.c_str(), "w", stdout);
 43 }
 44 
 45 
 46 inline int Getint()
 47 {
 48     int Ret = 0;
 49     char Ch = ‘ ‘;
 50     bool Flag = 0;
 51     while(!(Ch >= ‘0‘ && Ch <= ‘9‘))
 52     {
 53         if(Ch == ‘-‘) Flag ^= 1;
 54         Ch = getchar();
 55     }
 56     while(Ch >= ‘0‘ && Ch <= ‘9‘)
 57     {
 58         Ret = Ret * 10 + Ch - ‘0‘;
 59         Ch = getchar();
 60     }
 61     return Flag ? -Ret : Ret;
 62 }
 63 
 64 const int N = 10010, M = 24010;
 65 int n, m, k;
 66 int Fa[N];
 67 inline void Input()
 68 {
 69     scanf("%d%d%d", &n, &m, &k);
 70 }
 71 
 72 inline int Find(int x)
 73 {
 74     static int Arr[N], Length;
 75     Length = 0;
 76     while(x != Fa[x])
 77     {
 78         Arr[++Length] = x;
 79         x = Fa[x];
 80     }
 81     For(i, 1, Length) Fa[Arr[i]] = x;
 82     return x;
 83 }
 84 
 85 inline void Solve()
 86 {
 87     For(i, 1, n) Fa[i] = i;
 88     For(i, 1, m)
 89     {
 90         int u, v;
 91         scanf("%d%d", &u, &v);
 92         u = Find(u), v = Find(v);
 93         if(u != v) Fa[u] = v;
 94     }
 95 
 96     int Ans = 0;
 97     For(i, 1, n)
 98         if(Find(i) == i) Ans++;
 99     printf("%d\n", Ans - 1);
100 }
101 
102 int main()
103 {
104     #ifndef ONLINE_JUDGE
105     SetIO("H");
106     #endif
107     Input();
108     Solve();
109     return 0;
110 }