最小生成树
未优化Prim和Kruscal 自用模板
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import java.io.*;
import java.util.*;
public class Main {
static int[]pre;
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
PrintWriter pw=new PrintWriter(System.out);
while(sc.hasNext()){
int n=sc.nextInt();
int k=sc.nextInt();
pre=new int[n+1];
for(int i=0;i<=n;i++)pre[i]=i;
ArrayList<Line>list=new ArrayList<Line>();
for(int i=1;i<=k;i++){
list.add(new Line(sc.nextInt(),sc.nextInt(),sc.nextInt()));
}
Collections.sort(list);
int sum=0;
for(int i=0;i<list.size();i++){
Line temp=list.get(i);
if(find(temp.x)!=find(temp.y)){
sum+=temp.length;
union(temp.x,temp.y);
}
}
pw.println(sum);
pw.flush();
}
}
static int find(int x){
if(x==pre[x])return x;
else{
int root=find(pre[x]);
return pre[x]=root;
}
}
static void union(int a,int b){
int fa=find(a);
int fb=find(b);
if(fa!=fb){
pre[fa]=fb;
}
}
}
class Line implements Comparable<Line>{
int x,y;
int length;
Line(int x,int y,int length){
this.x=x;
this.y=y;
this.length=length;
}
public int compareTo(Line a) {
if(this.length<a.length)return -1;
if(this.length>a.length)return 1;
return 0;
}
}
import java.io.*;
import java.util.*;
public class Main {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
PrintWriter pw=new PrintWriter(System.out);
while(sc.hasNext()){
int n=sc.nextInt();
int[][]maze=new int[n][n];
int[]lowcost=new int[n];
boolean[]mst=new boolean[n];
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
maze[i][j]=sc.nextInt();
}
}
mst[0]=true;
for(int i=1;i<n;i++){
lowcost[i]=maze[0][i];
}
int index=-1;
int sum=0;
for(int i=1;i<n;i++){
int min=Integer.MAX_VALUE;
for(int j=0;j<n;j++){
if(!mst[j]&&lowcost[j]<min){
min=lowcost[j];
index=j;
}
}
mst[index]=true;
sum+=min;
for(int j=0;j<n;j++){
if(!mst[j]&&maze[index][j]<lowcost[j]){
lowcost[j]=maze[index][j];
}
}
}
pw.println(sum);
pw.flush();
}
}
}
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