二分+dijkstra

#include
using namespace std;
const int N = 2e5+10;
int g[1010][1010];
int n,m,k;
bool st[N];
int dist[N];
struct Edge{
	int a,b,c;
}edge[N];

bool check(int x){
	memset(g,0x3f,sizeof g);
	for(int i=1;i<=n;i++)g[i][i] = 0;
	for(int i=1;i<=m;i++){
		int a =edge[i].a,b = edge[i].b,c = edge[i].c;
		if(c<=x)g[a][b] = g[b][a] = 0;
		else g[a][b] = g[b][a] = 1;
	}
	
	
	memset(dist,0x3f,sizeof dist);
	dist[1] = 0;
	memset(st,0,sizeof st);
	
	for(int i=1;i<=n;i++){
		int t = -1;
		for(int j=1;j<=n;j++)
		 if(!st[j]&&(t==-1||dist[j]>n>>m>>k;
	for(int i=1;i<=m;i++){
		int a,b,c;cin>>a>>b>>c;
		edge[i] = {a,b,c};
	}
	
	int l = -1,r = 1000010 ;
	while(l+1!=r){
		int mid = l+r>>1;
		if(check(mid))r = mid;
		else l = mid;
	}
	
	if(r!=1000010)cout<