Time Limit: 1000MS | Memory Limit: 65536K | |
Total Submissions: 6456 | Accepted: 2816 |
Description
Realizing Farmer John will not pay her, Bessie decides to do the worst job possible. She must decide on a set of connections to install so that (i) the total cost of these connections is as large as possible, (ii) all the barns are connected together (so that it is possible to reach any barn from any other barn via a path of installed connections), and (iii) so that there are no cycles among the connections (which Farmer John would easily be able to detect). Conditions (ii) and (iii) ensure that the final set of connections will look like a "tree".
Input
* Lines 2..M+1: Each line contains three space-separated integers A, B, and C that describe a connection route between barns A and B of cost C.
Output
Sample Input
5 8 1 2 3 1 3 7 2 3 10 2 4 4 2 5 8 3 4 6 3 5 2 4 5 17
Sample Output
42
Hint
The most expensive tree has cost 17 + 8 + 10 + 7 = 42. It uses the following connections: 4 to 5, 2 to 5, 2 to 3, and 1 to 3.
题目大意:求一最大生成树
思路:这个题让我快崩溃了,WA了很多次,最后看discuss说有重边。。。改完AC了 疯了。。。
for(i=1;i<n;i++)
{
tree[i].s=1;
tree[i].e=i+1;
tree[i].l=dis[tree[i].s][tree[i].e];
}
for(i=1;i<n;i++)
{
int min=0;
for(j=i;j<n;j++)
if(tree[j].l>min)
{
min=tree[j].l;
m=j;
}
if(min==0)
{ flag=0; break; }
else
{
h=tree[i]; tree[i]=tree[m]; tree[m]=h;
for(j=i+1;j<n;j++)
if(tree[j].l<dis[tree[i].e][tree[j].e])
{
tree[j].s=tree[i].e;
tree[j].l=dis[tree[j].s][tree[j].e];
}
}
}
if(flag)
{
int s=0;
for(i=1;i<n;i++)
s+=tree[i].l;
cout<<s<<endl;
}
else
cout<<"-1"<<endl;
}
return 0;
}