【HDU1231】How Many Tables（并查集基础题）
什么也不用说，并查集裸题，直接盲敲即可。
1 #include <iostream> 2 #include <cstring> 3 #include <cstdlib> 4 #include <cstdio> 5 #include <cctype> 6 #include <cmath> 7 #include <algorithm> 8 #include <numeric> 9 using namespace std; 10 11 int father[1005]; 12 13 int getFather (int x) { 14 if (x != father[x]) { 15 father[x] = getFather(father[x]); 16 } 17 return father[x]; 18 } 19 20 void Union (int p, int q) { 21 int x = getFather (p); 22 int y = getFather (q); 23 if (x != y) { 24 father[y] = x; 25 } 26 } 27 28 void Init (int n) { 29 for (int i = 1 ; i <= n; ++ i) { 30 father[i] = i; 31 } 32 } 33 34 int main () { 35 int T; cin >> T; 36 while (T --) { 37 int n, op_n; 38 cin >> n >> op_n; 39 Init(n); 40 for (int i = 0 ; i < op_n; ++ i) { 41 int x, y; cin >> x >> y; 42 Union(x, y); 43 } 44 int cnt = 0; 45 for (int i = 1; i <= n; ++ i) { 46 if (father[i] == i) { 47 cnt ++; 48 } 49 } 50 cout << cnt << endl; 51 } 52 return 0; 53 }
1 import java.util.*; 2 import java.io.*; 3 import java.math.*; 4 5 class DisjointSet{ 6 public static int MAXX = 1005; 7 public int ans = 0; 8 public int father[] = new int[MAXX]; 9 public int vis[] = new int[MAXX]; 10 11 public DisjointSet(){ 12 this.ans = 0; 13 } 14 15 public int GetAns(){ 16 return ans; 17 } 18 public int GetFather(int x){ 19 if(father[x] != 0){ 20 return GetFather(father[x]); 21 } 22 else{ 23 return x; 24 } 25 } 26 27 public void Union(int x, int y){ 28 int fx = GetFather(x); 29 int fy = GetFather(y); 30 if(fx != fy){ 31 father[fy] = fx; 32 ans++; 33 } 34 } 35 } 36 37 public class Main{ 38 public static void main(String args[]){ 39 Scanner in = new Scanner(System.in); 40 int l = in.nextInt(); 41 int a, b, n, opn; 42 for(int i = 0; i < l; i++){ 43 n = in.nextInt(); 44 DisjointSet D = new DisjointSet(); 45 opn = in.nextInt(); 46 for(int j = 0; j < opn; j++){ 47 a = in.nextInt(); 48 b = in.nextInt(); 49 D.Union(a, b); 50 } 51 System.out.println(n - D.GetAns()); 52 } 53 } 54 }
