【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 }