HDU 1875

裸题呀~ 

无奈因为忘记排序wa了好几次~

代码比较丑，见谅~

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
using namespace std;
int n,t,m,k;
int p[105];
struct Edge
{
int u;
int v;
double w;
}edge[5010];
struct Island
{
double x;
double y;
}island[105];
bool cmp (Edge a ,Edge b)
{
return a.w < b.w;
}
int find(int x)
{
return p[x] == x ? x : x = find(p[x]);
}
double kruskal ()
{
for(int i = 0;i < n;i ++)
p[i] = i;
sort(edge,edge + k,cmp);
int num = 0;double ans = 0;
for(int i = 0; i < k; i ++)
{
int p1 = find(edge[i].u);
int p2 = find(edge[i].v);
if(p1 != p2)
{
ans += edge[i].w;
num ++;
p[p1]=find(p2);
}
if(num == n-1)
return ans;
}
return -1;
}
int main()
{
scanf("%d",&t);
while(t --)
{
scanf("%d",&n);
k = 0;
int flag = 1;
for(int i = 0;i < n;i ++)
{
scanf("%lf%lf",&island[i].x,&island[i].y);
}
for(int i = 0;i < n;i ++)
for(int j = i + 1;j < n;j ++)
{
double p = sqrt((island[i].x - island[j].x)*(island[i].x - island[j].x) + (island[i].y - island[j].y) * (island[i].y - island[j].y));
if(p >= 10 && p <= 1000)
{
edge[k].u = i;
edge[k].v = j;
edge[k].w = p;
k ++;
}
}
double ans;
if(k >= n-1)
ans = kruskal();
else flag = 0;
if(ans == -1 || flag == 0)
printf("oh!\n");
else
{
printf("%.1lf\n",ans*100);
}
}

return 0;
}


以前写的一种：

#include <iostream>
#include <cstdio>
#include <cmath>
#include <algorithm>
using namespace std;
int c;
int p[105];
struct Edge
{
int u;
int v;
double w;
}edge[10010];
bool cmp(Edge a,Edge b)
{
return a.w<b.w;
}
int find(int x)
{
return p[x]==x?x:p[x]=find(p[x]);
}
int main()
{
int t;
double x[105],y[105];
scanf("%d",&t);
while(t--)
{
double ans=0;
bool flag=true;
scanf("%d",&c);
for(int i=0;i<c;i++)
{
scanf("%lf%lf",&x[i],&y[i]);
}
int m=0;
for(int i=0;i<c;i++)
for(int j=i;j<c;j++)
{
edge[m].u=i;
edge[m].v=j;
edge[m].w=sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
m++;
}
sort(edge,edge+m,cmp);
for(int i=0;i<c;i++)
p[i]=i;
for(int i=0;i<m;i++)
{
int x=find(edge[i].u);
int y=find(edge[i].v);
if(x!=y)
{
if(edge[i].w<10)
{
continue;
}
else if(edge[i].w>1000)
{
flag=false;
break;
}
else
{
ans+=edge[i].w;
p[x]=y;

}
}
}
if(flag)
printf("%.1lf\n",ans*100);
else
printf("oh!\n");

}
return 0;
}