Blue Bridge Cup previous questions City construction minimum spanning tree

Take the dock as a 0-point deal.

First, determine whether the pier can generate a minimum spanning tree

Kruskal algorithm for minimum spanning tree, if for the side of cost <0, join directly

If possible: min (minimum spanning tree (not built pier), minimum spanning tree (built pier));

If not: minimum spanning tree (build pier)

#include "stdio.h" #include "string.h" #include "algorithm" using namespace std;int father[10010];struct link{int a,b,v;}    Link[110001];int Min (int a,int b) {if (a<b) return A; else return b;}    int fin (int x) {if (x==father[x]) return x;    Father[x]=fin (Father[x]); return father[x];} BOOL CMP (Link A,link b) {return A.V&LT;B.V;}    int Kruskal (int m) {int sum,i,fa,fb;    sum=0;        for (i=0;i<m;i++) {Fa=fin (LINK[I].A);        Fb=fin (LINK[I].B);            if (FA!=FB | | link[i].v<0) {SUM+=LINK[I].V;        FATHER[FA]=FB; }} return sum;}    int main () {int n,m,i,cnt,fa,fb,ans,x;    scanf ("%d%d", &n,&m);    for (i=0;i<=n;i++) father[i]=i;    for (i=0;i<m;i++) scanf ("%d%d%d", &AMP;LINK[I].A,&AMP;LINK[I].B,&AMP;LINK[I].V);    cnt=0;        for (i=1;i<=n;i++) {scanf ("%d", &x);            if (x!=-1) {link[m+cnt].a=0;            Link[m+cnt].b=i;        Link[m+cnt].v=x;    cnt++;        }} for (i=0;i<m;i++) {Fa=fin (LINK[I].A);        Fb=fin (LINK[I].B);    FATHER[FA]=FB;    } for (i=2;i<=n;i++) if (Fin (1)!=fin (i)) break;        if (i==n+1) {for (i=0;i<=n;i++) father[i]=i;        Sort (link,link+m,cmp);        Ans=kruskal (m);        for (i=0;i<=n;i++) father[i]=i;        Sort (link,link+m+cnt,cmp);        Ans=min (Ans,kruskal (m+cnt));    printf ("%d\n", ans);        } else {for (i=0;i<=n;i++) father[i]=i;        Sort (link,link+m+cnt,cmp);    printf ("%d\n", Kruskal (m+cnt)); } return 0;}

Blue Bridge Cup previous questions City construction minimum spanning tree