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#define ka1 getchar()
#define iis std::ios::sync_with_stdio(false)
using namespace std;
typedef long long LL;
const int N = 100005;
const int INF = 0x3f3f3f3f;
const LL mod = 10000;
const double eps = 1e-8;
struct {
int to;
LL w;
lp(int a,LL b){to=a;w=b;}
bool operator <(const lp &a)const {
if(w!=a.w) return w>a.w;
return to<a.to;
}
};
vector<lp>mp[N];
LL dis1[N],dis2[N];
int n,m;
void init(){
for(int i=0;i<=n;++i)mp[i].clear();
}
void dij(int s){
memset(dis1,0x3f,sizeof(dis1));
memset(dis2,0x3f,sizeof(dis2));
dis1[s]=0;
priority_queue<lp>Q;
Q.push(lp(s,0));
while(!Q.empty() ){
lp x=Q.top();Q.pop();
int u=x.to;
if(dis2[u]<x.w)continue;
for(int i=0;i<mp[u].size();++i){
lp y=mp[u][i];
if(dis2[y.to]>(x.w+y.w)){
dis2[y.to]=x.w+y.w;
Q.push(lp(y.to,dis2[y.to]));
}
if(dis2[y.to]<dis1[y.to]){
swap(dis2[y.to],dis1[y.to]);
}
}
}
printf("%lldn",dis2[n]);
}
int main(){
int t;
scanf("%d",&t);
while(t--){
int a,b,c;
scanf("%d%d",&n,&m);
init();
for(int i=0;i<m;++i){
scanf("%d%d%d",&a,&b,&c);
mp[a].push_back(lp(b,c));
mp[b].push_back(lp(a,c));
}
dij(1);
}
return 0;
}
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