The Unique MST

  1 #include<iostream>
  2 #include<cstdio>
  3 #include<cmath>
  4 #include<algorithm>
  5 #include<string>
  6 #include<cstring>
  7 #include<vector>
  8 #include<queue>
  9 #define lson l,mid,rt<<1
 10 #define rson mid+1,r,rt<<1|1
 11 #define N 250500
 12 #define MOD 1e9+7
 13 #define INF 0x3f3f3f3f
 14 typedef long long ll;
 15 using namespace std;
 16 struct sair{
 17     int x,y,v;
 18 }a[100005];
 19 int fa[1005];
 20 int n,m;
 21 bool cmp(sair a,sair b){
 22     return a.v<b.v;
 23 }
 24 
 25 int Find(int x){
 26     int r=x,y;
 27     while(x!=fa[x]){
 28         x=fa[x];
 29     }
 30     while(x!=r){
 31         y=fa[r];
 32         fa[r]=x;
 33         r=y;
 34     }
 35     return x;
 36 }
 37 
 38 int join(int x,int y){
 39     int xx=Find(x);
 40     int yy=Find(y);
 41     if(xx==yy){
 42         return 0;
 43     }
 44     fa[xx]=yy;
 45     return 1;
 46 }
 47 
 48 vector<int>v;
 49 
 50 
 51 int check(int xxx){
 52     int ans=0;
 53     int xxxx=1;
 54     for(int i=1;i<=n;i++){
 55         fa[i]=i;
 56     }
 57     for(int i=1;i<=m;i++){
 58         if(i!=xxx){
 59             if(join(a[i].x,a[i].y)){
 60                 ans+=a[i].v;
 61                 xxxx++;
 62             }
 63         }
 64     }
 65     if(xxxx==n)
 66         return ans;
 67     return -1;
 68 }
 69 
 70 int main(){
 71     std::ios::sync_with_stdio(false);
 72     int t;
 73     cin>>t;
 74     while(t--){
 75         cin>>n>>m;
 76         for(int i=1;i<=n;i++){
 77             fa[i]=i;
 78         }
 79         for(int i=1;i<=m;i++){
 80             cin>>a[i].x>>a[i].y>>a[i].v;
 81 
 82         }
 83         int ans1=0;
 84         v.clear();
 85         sort(a+1,a+m+1,cmp);
 86         for(int i=1;i<=m;i++){
 87             if(join(a[i].x,a[i].y)){
 88                 ans1+=a[i].v;
 89                 v.push_back(i);
 90             }
 91         }
 92         int flag=1;
 93         for(int i=0;i<v.size();i++){
 94             if(check(v[i])==ans1){
 95                 flag=0;
 96                 break;
 97             }
 98         }
 99         if(flag){
100             cout<<ans1<<endl;
101         }
102         else{
103             cout<<"Not Unique!"<<endl;
104         }
105     }
106 }