HDU 1233 还是畅通工程 （最小生成树、并查集）

VJ题目链接

题意题目都很简单，最小生成树，然后用并查集来判断是否已经连入图中

import java.util.PriorityQueue;import java.util.Scanner;class Road implements Comparable<Road>{int a,b,dis;public Road(int a,int b,int dis) {this.a=a;this.b=b;this.dis=dis;}@Overridepublic int compareTo(Road o) {if(dis!=o.dis) {return dis-o.dis;}else {if(a!=o.a)return a-o.a;elsereturn b-o.b;}}}public class Main{static Scanner sc = new Scanner(System.in);static int n,m,cnt;static int [] dad;static PriorityQueue<Road> pq=new PriorityQueue<Road>();static void init() {cnt=0;for(int i=1;i<=n;i++) dad[i]=i;}static int find(int x) {if(x==dad[x]) return x;else {dad[x]=find(dad[x]);return dad[x];}}static void union(int x,int y) {int dx=find(x);int dy=find(y);if(dx==dy) {return;}if(dx>dy)dad[dx]=dy;elsedad[dy]=dx;}public static void main(String[] args) {while(sc.hasNext()) {n=sc.nextInt();if(n==0) break;dad=new int[n+1];init();pq.clear();int len=n*(n-1)/2;for(int i=0;i<len;i++) {pq.add(new Road(sc.nextInt(),sc.nextInt(),sc.nextInt()));}Road tmp;while(!pq.isEmpty()) {tmp=pq.poll();if(find(tmp.a)==find(tmp.b)) continue;else {union(tmp.a,tmp.b);cnt+=tmp.dis;}}System.out.println(cnt);}System.exit(0);}}