程式碼：

#include<cstdio>
#include<vector>
#include<cstring>
#include<algorithm>
using namespace std;

#define maxn 100
#define maxm 10000
#define read(x) scanf("%d",&x)

struct Edge{
	int x,y,z;
	Edge(){}
	Edge(int xx,int yy,int zz) {
		x=xx,y=yy,z=zz;
	}
	bool operator < (const
 
 Edge& oth) const {
		return z<oth.z;
	}
};

int n,m;
Edge e[maxm+5];
int fa[maxn+5];
bool intree[maxm+5];

int find(int x) {
	if(fa[x]) return fa[x]=find(fa[x]);
	return x;
}

vector<Edge> g[maxn+5];

int kruskal() {
	int s=0;
	sort(e+1,e+m+1);
	for(int i=1;i<=m;i++) {
		int fa1=find
 
(e[i].x),fa2=find(e[i].y);
		if(fa1==fa2) continue;
		fa[fa1]=fa2;
		s+=e[i].z;
		intree[i]=true;
		g[e[i].x].push_back(e[i]);
		g[e[i].y].push_back(Edge(e[i].y,e[i].x,e[i].z));
	}
	return s;
}

bool isuse[maxm+5];
int d[maxn+5][maxn+5];

void init() {
	memset(d,0,sizeof(d));
	memset(isuse,0,sizeof(isuse)
 
);
	memset(intree,0,sizeof(intree));
	memset(fa,0,sizeof(fa));
	for(int i=1;i<=n;i++) g[i].clear();
}

void dfs(int x,int fa,int y) {
	for(int i=1;i<=n;i++) {
		if(isuse[i]) d[x][i]=d[i][x]=max(d[fa][i],y);
	}
	isuse[x]=true;
	for(int i=0;i<g[x].size();i++) {
		if(isuse[g[x][i].y]) continue;
		dfs(g[x][i].y,x,g[x][i].z);
	}
}

int sec() {
	int ans=1e9;
	for(int i=1;i<=m;i++) {
		if(!intree[i]) {
			ans=min(ans,-d[e[i].x][e[i].y]+e[i].z);
		}
	}
	return ans;
}

int main() {
	int T;
	read(T);
	while(T--) {
		read(n),read(m);
		init();
		for(int i=1;i<=m;i++) {
			int x,y,z;
			read(x),read(y),read(z);
			e[i]=Edge(x,y,z);
		}
		int ans=kruskal();
		dfs(1,0,0);
		int ans2=sec()+ans;
		if(ans==ans2) printf("Not Unique!\n");
		else printf("%d\n",ans);
	}
	
	return 0;
}