1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
|
#include<bits/stdc++.h>
using namespace std;
const int maxn = 110;
int n,m;
struct edge{
int from,to,dist;
edge(){}
edge(int f,int t,int d):from(f),to(t),dist(d){}
bool operator<(const edge &r)const{
return dist<r.dist;
}
};
struct Kruskal{
vector<int> G[maxn];
int m,n;
int par[maxn];
vector<edge> edges;
int done;
void init(int n){
this->n = n;
for(int i=0;i<=n;i++)G[i].clear();
edges.clear();
for(int i=0;i<n;i++)par[i] = i;
}
void addedge(int from,int to,int dist){
edges.push_back(edge(from,to,dist));
m = edges.size();
G[from].push_back(m-1);
done = 0;
}
int getroot(int a){
if(par[a]==a)return a;
par[a] = getroot(par[a]);
return par[a];
}
void merge(int a,int b){
int p1 = getroot(a);
int p2 = getroot(b);
if(p1==p2)return;
par[p2] = p1;
}
int kruskal(){
int res = 1e9;
sort(edges.begin(),edges.end());
for(int k=0;k<edges.size();k++){//枚举起点
done = 0;
for(int p=0;p<n;p++)par[p] = p;
int i;
for(i=k;i<edges.size();i++){
if(getroot(edges[i].from)!=getroot(edges[i].to)){
merge(edges[i].from,edges[i].to);
++done;
}
if(done==n-1)break;
}
if(done==n-1)res = min(res,edges[i].dist-edges[k].dist);//更新
}
return res;
}
}solver;
int main(){
//freopen("in.txt","r",stdin);
//freopen("out.txt","w",stdout);
while(scanf("%d%d",&n,&m)&&(n+m)){
solver.init(n);
for(int i=0;i<m;i++){
int a,b,c;
scanf("%d%d%d",&a,&b,&c);
a--;
b--;
solver.addedge(a,b,c);
solver.addedge(b,a,c);
}
int res = solver.kruskal();
printf("%dn",res==1e9?-1:res);
}
return 0;
}
|
近期评论