1.给N个点 建立一支最小生成树

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
using namespace std;
const int maxn=207;
int n,m;
int d[maxn][maxn];
int dis[maxn],ans;
bool v[maxn];
int main(){
	while(scanf("%d",&n)!=EOF&&n) {
		char a,b;
		int m,x;
		memset(d,0x3f3f3f,sizeof(d));
		memset(v, 0, sizeof(v));
    	memset(dis,0x3f3f3f,sizeof(dis));
		
		for(int i=1;i<n;i++) {
			cin>>a>>m;
			while(m--){
				cin>>b>>x;
				d[a-'A'][b-'A']=d[b-'A'][a-'A']=min(d[a-'A'][b-'A'],x);
				//cout<<d[a-'A'][b-'A']<<endl;
			}
		}
		for(int i=0;i<n;i++) d[i][i]=0;
		dis[0]=0;
		for(int i=1;i<n;i++){
			int x=206;
			for(int j=0;j<n;j++) {
				if(!v[j]&&dis[j]<dis[x]) x=j;
			}
			v[x]=1;
			for(int j=0;j<n;j++ ) {
				if(!v[j]) dis[j]=min(dis[j],d[x][j]);
			}
		}
		ans=0;
		for(int i=1;i<n;i++) {
			//cout<<dis[i]<<" ";
			ans+=dis[i];
		}
		cout<<ans<<endl;
	}

2.Networking
同上 不同的是下标一个是1一个是0

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
using namespace std;
const int maxn=507;
int n,m;
int d[maxn][maxn];
int dis[maxn],ans;
bool v[maxn];
int main(){
	while(cin>>n>>m&&n){
		int a,b,c;
		memset(d,0x3f3f3f,sizeof(d));
		for(int i=1;i<=m;i++){
			cin>>a>>b>>c;
			d[a][b]=min(d[a][b],c);
			d[b][a]=d[a][b];
		}
		for(int i=1;i<=n;i++){
			d[i][i]=0;
		}
		memset(v, 0, sizeof(v));
	    memset(dis,0x3f3f3f,sizeof(dis));
	    dis[1]=0;
	    for(int i=1;i<n;i++){
	    	int x=0;
	    	for(int j=1;j<=n;j++) if(!v[j]&&dis[j]<dis[x]) x=j;
	    	v[x]=1;
	    	for(int j=1;j<=n;j++) if(!v[j]) dis[j]=min(dis[j],d[x][j]);
		}
		ans=0;
		for(int i=2;i<=n;i++) {
			//cout<<dis[i]<<" ";
			ans+=dis[i];
		}
		cout<<ans<<endl;
	}
} 

3.Building a Space Station
依然是板子
要注意的是球心之间的距离 - 两个球的半径如果 < 0 则说明是覆盖的，此时的距离按照0计算

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#define inf 0x7f7f7f7f
using namespace std;
struct node{
	double x,y,z,r;
}q[101];
bool v[101];
double d[101][101],dis[101];

int main(){
	int n;
	while(scanf("%d",&n)&&n){
		double s;
		memset(d,0,sizeof(d));
		for(int i=1;i<=n;i++) {
			scanf("%lf %lf %lf %lf",&q[i].x,&q[i].y,&q[i].z,&q[i].r);
		}
		for(int i=1;i<n;i++){
			for(int j=i+1;j<=n;j++){
				s= sqrt((q[i].x-q[j].x)*(q[i].x-q[j].x)+(q[i].y-q[j].y)*(q[i].y-q[j].y)+(q[i].z-q[j].z)*(q[i].z-q[j].z))-q[i].r-q[j].r;	
				if(s>0) {
					d[i][j]=d[j][i]=s;
				}
				else d[i][j]=d[j][i]=0;
				
			}
		}
		for(int i=1;i<=n;i++){
			d[i][i]=0;
		}
		memset(v, 0, sizeof(v));
	    memset(dis,0x7f7f7f7f,sizeof(dis));
	    dis[1]=0;
	    for(int i=1;i<n;i++){
	    	int x=0;
	    	for(int j=1;j<=n;j++) if(!v[j]&&dis[j]<dis[x]) x=j;
	    	v[x]=1;
	    	for(int j=1;j<=n;j++) if(!v[j]) dis[j]=min(dis[j],d[x][j]);
		}
		double ans=0;
		for(int i=2;i<=n;i++) {
			//cout<<dis[i]<<" ";
			ans+=dis[i];
		}
		printf("%.3lf\n",ans);
	}
}