作者:手机用户2502905647 | 来源:互联网 | 2023-09-13 18:15
描述Youhavencomputersnumberedfrom1tonandyouwanttoconnectthemtomakeasmalllocalareanetwork(L
描述
You have
n computers numbered from 1 to n and you want to connect them
to make a small local area network (LAN). All connections are two-way (that is
connecting computers i and j is the same as connecting
computers j and i). The cost of connecting computer i
and computer j is cij. You cannot connect some
pairs of computers due to some particular reasons. You want to connect them so
that every computer connects to any other one directly or indirectly and you
also want to pay as little as possible.
Given n and each cij , find the cheapest way to
connect computers.
输入
There are
multiple test cases. The first line of input contains an integer T
(T <= 100), indicating the number of test cases. Then T
test cases follow.
The first line of each test case contains an integer n (1 <
n <= 100). Then n lines follow, each of which contains
n integers separated by a space. The j-th integer of the
i-th line in these n lines is cij,
indicating the cost of connecting computers i and j
(cij = 0 means that you cannot connect them). 0 <=
cij <= 60000, cij =
cji, cii = 0, 1 <= i,
j <= n.
输出
For each test
case, if you can connect the computers together, output the method in in the
following fomat:
i1 j1 i1
j1 ......
where ik ik (k >= 1) are the
identification numbers of the two computers to be connected. All the integers
must be separated by a space and there must be no extra space at the end of the
line. If there are multiple solutions, output the lexicographically
smallest one (see hints for the definition of "lexicography
small") If you cannot connect them, just output "-1" in the
line.
样例输入
2
3
0 2 3
2 0 5
3 5 0
2
0 0
0 0
样例输出
1 2 1 3
-1
提示
A
solution A is a line of p integers: a1,
a2, ...ap.
Another solution
B different from A is a line of q integers:
b1, b2,
...bq.
A is lexicographically
smaller than B if and only if:
(1) there exists a positive
integer r (r <= p, r <= q)
such that ai = bi for all 0 <
i <r and ar <
br
OR
(2) p <q
and ai = bi for all 0 <i
<= p
题目来源
>ZJCPC 2009
主要是选取权值最小的边构成树,kruskal+并查集
选完之后保存起来,还需要二次字典序排。
#include
#include
#include
using namespace std;
const int MAXN=120;
int N,cnt;
int lis[MAXN];
struct node{
int u,v,w;
}edge[MAXN*60];
struct r{
int a,b;
}ans[MAXN];
int find(int x){
int temp=lis[x];
while(temp!=lis[temp]){
temp=lis[temp];
}
return temp;
}
void merge(int x, int y){
lis[x]=y;
}
bool cmp1(node a, node b){
if(a.w!=b.w)return a.w < b.w;
return a.u < b.u;
}
bool cmp2(r a, r b){
if(a.a!=b.a)return a.a < b.a;
return a.b < b.b;
}
int kruskal(){
int flag=0;
sort(edge,edge+cnt,cmp1);
for(int i=0; i){
int x=find(edge[i].u);
int y=find(edge[i].v);
if(x!=y){
merge(x,y);
ans[flag].a=edge[i].u;
ans[flag].b=edge[i].v;
flag++;
}
}
return flag;
}
int main(int argc, char *argv[])
{
int T,v;
scanf("%d",&T);
while(T--){
cnt=0;
scanf("%d",&N);
for(int i=1; i<=N; i++){
lis[i]=i;
}
for(int i=1; i<=N; i++){
for(int j=1; j<=N; j++){
scanf("%d",&v);
if(i0){
edge[cnt].u=i;
edge[cnt].v=j;
edge[cnt].w=v;
cnt++;
}
}
}
int f=kruskal();
if(f!=N-1){
printf("-1\n");
}else{
int flag=0;
sort(ans,ans+f,cmp2);
for(int i=0; i){
if(flag)printf(" ");
printf("%d %d",ans[i].a,ans[i].b);
flag=1;
}
printf("\n");
}
}
return 0;
}