模板整理——图论·最小生成树·Kruskal

#include<cmath>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int fa[105];
struct node
{
int u,v,l;
}e[105];
bool cmp(node t1,node t2)
{
return t1.l<t2.l;
}
int Find(int u)
{
if (u==fa[u]) return u;
fa[u]=Find(fa[u]);
return fa[u];
}
void Union(int u,int v)
{
int x=Find(u),y=Find(v);
fa[y]=x;
}
int main()
{
int n,m;
scanf("%d%d",&m,&n);
while (m!=0)
{
int num=0;
for (int i=1; i<=n; i++) fa[i]=i;
memset(e,0,sizeof(e));
for (int i=1; i<=m; i++)
{
int u,v,l;
scanf("%d%d%d",&u,&v,&l);
e[++num].u=u;
e[num].v=v;
e[num].l=l;
}
sort(e+1,e+1+num,cmp);
int s=0,ans=0;
for (int i=1; i<=num; i++)
{
int u=e[i].u,v=e[i].v;
if (Find(u)!=Find(v))
{
s++;
Union(u,v);
ans+=e[i].l;
if (s==n-1) break;
}
}
if (s<n-1) printf("?\n");
else printf("%d\n",ans);
scanf("%d%d",&m,&n);
}
return 0;
}