【BZOJ】1196: [HNOI2006]公路修建问题

#include<stdio.h>
#include<algorithm>
using namespace std;
#define Bool inline bool
#define cint const int &
#define N 20005

int n,k,m,f
,p1
,c1
,p2
,c2
,u
,v
;

Bool cmp1(cint a,cint b){return c1[a]<c1[b];}
Bool cmp2(cint a,cint b){return c2[a]<c2[b];}

int gf(cint a){return f[a]==a?a:f[a]=gf(f[a]);}

Bool judge(cint mid)
{
for (int i=1;i<=n;i++) f[i]=i;int tot=0;
for (int i=1;i<=m && c1[p1[i]]<=mid && tot<n-1;i++) if (gf(u[p1[i]])!=gf(v[p1[i]])) f[f[u[p1[i]]]]=f[v[p1[i]]],tot++;
if (tot<k) return 0;
for (int i=1;i<=m && c2[p2[i]]<=mid && tot<n-1;i++) if (gf(u[p2[i]])!=gf(v[p2[i]])) f[f[u[p2[i]]]]=f[v[p2[i]]],tot++;
return tot==n-1;
}

int main()
{
scanf("%d%d%d",&n,&k,&m);m-=1;
for (int i=1;i<=m;i++) scanf("%d%d%d%d",u+i,v+i,c1+i,c2+i),p1[i]=i,p2[i]=i;
sort(p1+1,p1+m+1,cmp1);sort(p2+1,p2+m+1,cmp2);
int l=1,r=30000;
for (int mid=15000;l<r;mid=l+r>>1) if (judge(mid)) r=mid;else l=mid+1;
printf("%d",l);
}